System And Method For Determining Airtime Using Free Fall

ABSTRACT

A system for determining airtime of a moving sportsman includes at least one accelerometer for detecting vibration or acceleration of the sportsman. A processor in communication with the at least one accelerometer processing signals from the accelerometer to determine free-fall. A pressure sensor may be used to determine change in altitude and the processor may process signals from the pressure sensor with the accelerometer signals to determine airtime and drop distance during free-fall. A method for determining airtime of a moving sportsman includes processing data from one or more accelerometers attached to the sportsman, to determine when the sportsman is in free-fall, and determining a time period corresponding to the free-fall.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/598,410, filed Nov. 13, 2006, which is a divisional application ofU.S. application Ser. No. 11/221,029, filed Sep. 5, 2005 (now U.S. Pat.No. 7,162,392), which is a continuation of U.S. patent application Ser.No. 10/921,743, filed Aug. 19, 2004 (now U.S. Pat. No. 7,092,846), whichis a divisional of U.S. patent application Ser. No. 10/283,642, filedOct. 30, 2002 (now U.S. Pat. No. 6,959,259), which is a continuation ofU.S. patent application Ser. No. 09/089,232, filed Jun. 2, 1998 (nowU.S. Pat. No. 6,539,336), which (a) claims priority to U.S. ProvisionalApplication No. 60/077,251, filed on Mar. 9, 1998, (b) is acontinuation-in-part of U.S. application Ser. No. 08/867,083, filed Jun.2, 1997 (now U.S. Pat. No. 6,266,623), which is a continuation-in-partof U.S. patent application Ser. No. 08/344,485, filed Nov. 21, 1994 (nowU.S. Pat. No. 5,636,146), and (c) is a continuation-in-part of U.S.application Ser. No. 08/764,758, filed Dec. 12, 1996 (now U.S. Pat. No.5,960,380). This application is also a continuation of U.S. applicationSer. No. 10/842,947, filed May 11, 2004 (now U.S. Pat. No. 7,072,789),which is a continuation of U.S. application Ser. No. 09/992,966, filedNov. 6, 2001 (now U.S. Pat. No. 6,885,971), which is also a continuationof U.S. application Ser. No. 09/089,232. This application is also acontinuation-in-part of U.S. application Ser. No. 10/289,039, filed Nov.6, 2002 (now U.S. Pat. No. 6,963,818), which is a continuation of U.S.application Ser. No. 09/784,783, filed Feb. 15, 2001 (now U.S. Pat. No.6,516,284), which is a continuation of U.S. application Ser. No.09/353,530, filed Jul. 14, 1999 (now U.S. Pat. No. 6,496,787), which isa continuation of U.S. application Ser. No. 08/764,758. This applicationis also a continuation-in-part of U.S. application Ser. No. 10/950,897,filed Sep. 27, 2004 (now U.S. Pat. No. 7,054,784), which is a divisionalof U.S. patent application Ser. No. 10/234,660, filed Sep. 4, 2002 (nowU.S. Pat. No. 6,856,934), which is a continuation of U.S. applicationSer. No. 09/886,578, filed Jun. 21, 2001 (now U.S. Pat. No. 6,498,994),which is a continuation of U.S. application Ser. No. 08/867,083.

FIELD OF THE INVENTION

The invention relates generally to monitoring and quantifying sportmovement (associated either with the person or with the vehicle used orridden by the person), including the specific parameters of “air” time,power, speed, and drop distance. The invention also has “gaming” aspectsfor connecting users across the Internet. The invention is particularlyuseful in sporting activities such as skiing, snowboarding, mountainbiking, wind-surfing, skate-boarding, roller-blading, kayaking, racing,and running, in which sporting persons expend energy, catch “air”, moveat varying speeds, and perform jumps.

BACKGROUND OF THE INVENTION

It is well known that many skiers enjoy high speeds and jumping motionswhile traveling down the slope. High speeds refer to the greater andgreater velocities which skiers attempt in navigating the slopesuccessfully (and sometimes unsuccessfully). The jumping motions, on theother hand, include movements which loft the skier into the air.Generally, the greater the skier's speed, the higher the skier's loftinto the air.

The interest in high speed skiing is apparent simply by observing thevelocity of skiers descending the mountain. The interest in the loftmotion is less apparent; although it is known that certain enthusiasticsnowboarders regularly exclaim “let's catch some air” and other assortedremarks when referring to the amount and altitude of the lofting motion.

The sensations of speed and jumping are also readily achieved in othersporting activities, such as in mountain biking, skating,roller-blading, wind-surfing, and skate-boarding. Many mountain bikersand roller-bladers, like the aforementioned skiers, also crave greaterspeeds and “air” time.

However, persons in such sporting activities only have a qualitativesense as to speed and loft or “air” time. For example, a typicalsnowboarder might regularly exclaim after a jump that she “caught” some“big sky,” “big air” or “phat air” without ever quantitatively knowinghow much time really elapsed in the air.

Speed or velocity also remain unquantified. Generally, a person such asa skier can only assess whether they went “fast”, “slow” or “average”,based on their perception of motion and speed (which can be grosslydifferent from actual speed such as measured with a speedometer or radargun).

There are also other factors that sport persons sometimes assessqualitatively. For example, suppose a snowboarder skis a double-diamondski slope while a friend skis a green, easy slope. When they both reachthe bottom, the “double-diamond” snowboarder will have expended moreenergy than the other, generally, and will have worked up a sweat; whilethe “green” snowboarder will have had a relatively inactive ride downthe slope. Currently, they cannot quantitatively compare how rough theirjourneys were relative to one another.

OBJECTS OF THE INVENTION

It is, accordingly, an object of the invention to provide systems andmethods for determining “air” time associated with sport movements.

It is another object of the invention to provide systems and methods fordetermining the speed of participants and/or vehicles associated withsport movements.

It is yet another object of the invention to provide improvements tosporting vehicles which are ridden by sporting participants, and whichprovide a determination of speed, airtime, drop distance and/or power ofthe vehicle.

Still another object of the invention is to provide systems and methodsfor determining the amount of “power” or energy absorbed by a personduring sporting activities. One specific object is to provide a gauge ofenergy spent by a sporting participant as compared to others in the samesport, to provide a quantitative comparison between two or moreparticipants.

Yet another object of the invention is to provide the “drop distance”associated with a jump; and particularly the drop distance which occurswithin “airtime”.

Still another object of the invention is to provide a gaming system toquantitatively compare airtime, drop distance, power, and/or speedbetween several participants, regardless of their location.

These and other objects of the invention will become apparent in thedescription which follows.

SUMMARY OF THE INVENTION

As discussed herein, “air” or “loft” time (or “airtime”) refer to thetime spent off the ground during a sporting movement. For example,airtime according to the invention can include a snowboarder catchingair off of a mogul or a ledge. Typically, airtime is greater thanone-half (or one-third) second and less than six seconds. In “extreme”sporting events, the maximum airtime can increase up to about ten orfifteen seconds.

In most cases, it is useful to specify the lower and upper limits ofairtime—e.g., from one second to five seconds—so as to reduce processingrequirements and to logic out false airtime data. More particularly, thefollowing description provides several techniques and methods fordetermining airtime. One technique, for example, monitors the vibrationof the user's vehicle (e.g., a ski or snowboard) moving on the ground;and senses when the vibration is greatly reduced, indicating that thevehicle is off the ground. However, when such a user stands in line forthe chair-lift, she might remain motionless for thirty seconds or more.By restricting the upper limit to five seconds, a system of theinvention can be made to ignore conditions such as standing in line.Similarly, when a user walks slowly, there are cyclical periods ofrelatively small vibration (e.g., when the user lifts his foot off theground). Therefore, a lower limit of one-half second or one second areappropriate; so that any detected “airtime” that falls below that lowerlimit is ignored and not stored.

In another aspect of the invention, the measurement of airtime is usedto quantify the efficiency by which a person or sport vehicle remain onthe ground. By way of example, speed skiers desire to remain on theground; and the invention thus provides a system which monitors theperson and/or vehicle (e.g., the slalom ski) to detect airtime. Thisinformation is fed back to the person (in real time or in connectionwith a later review of video) so that he or she can improve theirposture to reduce unwanted airtime. In such applications, airtime istypically less than about three or four seconds; and the lower limit isessentially zero (that is, providing miniscule airtime data can beappropriate for training purposes).

As used herein, “power” refers to the amount of energy expended by aperson or vehicle during a sporting activity, typically over a periodsuch as one ski run. The following description provides several systems,techniques and methods for determining power. Power need not correspondto actual energy units; but does provide a measure of energy expended bythe person or vehicle as compared to other persons and vehicles in thesame sporting activity. Power can be used to quantify “bragging rights”between sport enthusiasts: e.g., one user can quantify that he expendedmore energy, or received more “punishment”, as compared to a friend.Power can refer to the amount of “G's” absorbed during a given period ofactivity. Power is typically quantified over a period that is selectableby the user. For example, power can be determined over successiveone-second periods, or successive five second periods, or successive oneminute periods, or successive five minute periods, or other periods.Power can also be measured over a manually selected period. For example,two snowboarders can initialize the period at the beginning of a rundown a ski slope and can stop their period at the end of the run.

“Speed” refers the magnitude of velocity as measured during a sportactivity. Speed generally refers to the forward direction of the movingsportsman.

“Drop distance” refers to the height above the ground as experienced bya user or vehicle during a sport activity. Drop distance preferablycorresponds to a measured airtime period. For example, a snowboarder whotakes a jump off of a ledge might drop thirty feet (drop distance) inthree seconds (airtime). Drop distance can also specifically refer tomaximum height above the ground for a given jump (for example, a user ona flat surface can first launch upwards off a jump and return to thesame level but experience a five foot drop distance).

The invention thus provides systems and methods for quantifying airtime,power, speed and/or drop distance to quantify a user's sport movementwithin one or more of the following activities: skiing, snowboarding,wind-surfing, skate-boarding, roller-blading, kayaking, white waterracing, water skiing, wake-boarding, surfing, racing, running, andmountain biking. The invention can also be used to quantify theperformance of vehicles upon which users ride, e.g., a snowboard or skior mountain bike.

The following U.S. patents provide useful background for the inventionand are herein incorporated by reference: U.S. Pat. No. 5,343,445; U.S.Pat. No. 4,371,945; U.S. Pat. No. 4,757,714; U.S. Pat. No. 4,089,057;U.S. Pat. No. 4,722,222; U.S. Pat. No. 5,452,269; U.S. Pat. No.3,978,725; and U.S. Pat. No. 5,295,085.

In one aspect, the invention provides a sensing unit which includes acontroller subsystem connected with one or more of the following sensors(each of which is described herein): an airtime sensor, a speed sensor,a power sensor, and a drop distance sensor. The controller subsystemincludes a microprocessor or microcontroller and can includepreamplifiers and A/D converters to interface with the sensor(s)(alternatively, the sensor contains such circuitry). The controllersubsystem can further include logic circuitry and/or software modules tologic out unwanted data from the sensors (e.g., airtime data that doesnot correspond to reasonable loft times). Preferably, the controllersubsystem also includes digital memory to store parameters for thesensors and to store data such as power, airtime, speed and dropdistance (collectively “performance data”) for later retrieval. Abattery typically is used to power the controller subsystem. The batterycan also be used for the sensors, if required. However, one preferredsensor which can function for any of the sensors is the piezoelectricfoils such as made from AMP SENSORS™. These foils do not require powerand rather generate a voltage in response to input forces such as sound.A display can be integrated with the sensing unit to provide directfeedback to the performance data. In one aspect, a user interface isalso integrated with the sensing unit to provide user control of thesensing unit, e.g., to include an ON/OFF switch and buttons to selectfor acquisition or display of certain performance data.

The sensing unit of one aspect is a stand-alone unit, and thus includesa housing. The housing is rugged to survive rigorous sporting activity.Preferably, the housing provides a universal interface which permitsmounting of the unit to a variety of vehicle platforms, e.g., onto aski, snowboard, mountain bike, windsurfer, roller blades, etc. Theuniversal interface is preferably a conformal surface which convenientlypermits mounting of the sensing unit to a plurality of surfaces, e.g., aflat surface such as a snowboard, and a round bar such as on a mountainbike.

Alternatively, the sensing unit can be integrated into objects alreadyassociated with the sporting activity. In one aspect, the sensing unitis integrated into the ski boot or other boot. In another aspect, thesensing unit is integrated into the binding for a ski boot orsnowboarder boot. In still another aspect, the sensing unit isintegrated into a ski, snowboard, mountain bike, windsurfer, windsurfermast, roller blade boot, skate-board, kayak, or other sport vehicle.Collectively, the sport objects such as the ski boot and the variety ofsport vehicles are denoted as “sport implements”. Accordingly, when thesensing unit is not “stand alone”, the housing which integrates thecontroller subsystem with one or more sensors and battery can be madefrom the material of the associated sport implement, in whole or inpart, such that the sensing unit becomes integral with the sportimplement. The universal interface is therefore not desired in thisaspect.

In one preferred aspect, the sensing unit provides for the measurementof power entirely within a watch. Manufacturers such as CASIO™, TIMEX™,SEIKO™, FILA™, and SWATCH™ make sport wrist-watches with certain digitalelectronics disposed therein. In accord with the invention, powermeasurement capability is added within such a watch so that “power” datacan be provided to sport enthusiasts in all sports, e.g., volleyball,soccer, football, karate, and similar common sports.

In one preferred aspect, the performance data is transmitted viaradiofrequencies (or other data transfer technique, including infraredlight or inductively-coupled electronics) from the sensing unit to adata unit which is ergonomically compatible with the user. Accordingly,the sensing unit in this aspect does not require a display asperformance data is made available to the user through the data unit.For example, the data unit of one aspect is a watch that the user wearson her wrist. The data unit can alternatively be made into a“pager-like” module such as known fully in the art (MOTOROLA™ is onewell-known manufacturer that makes pager modules). In either case, thesensing unit and the data unit cooperate to provide a complete systemfor the user.

The data unit can take other forms, in other aspects. For example, theperformance data can be transmitted directly to a radio receiverconnected to headphones worn by the user or to a small speaker worn inthe user's ear. The radio receiver is for example similar to the SONY®WALKMAN®, used by plenty of sports enthusiasts. In accord with thisaspect of the invention, the sensing unit transmits performance datadirectly into the receiver so that the user can listen—in real time—tothe results of his sports performance. Specifically, the radio receiverincludes a data conversion unit which responds to the receipt ofperformance data from the sensing unit and which converts theperformance data into sound, via the headphones, so that the userlistens to the performance data. After a jump, for example, the dataconversion unit transmits airtime and drop distance data to the user sothat the user hears “1.8 seconds of air, 5 feet drop distance”.

The data unit can also be made into the pole of a skier, such that adisplay at the end of the pole provides performance data to the user.

In still another aspect, the data unit is not required. Rather,performance data is transmitted such as by RF directly from the sensingunit to a base station associated with the sporting area. For example,the base station can be a computer in the lodge of a ski area. Thesensing unit of this aspect transmits performance data tagged to aparticular user to the base station where performance data from allusers is collated, stored, compared and/or printed for various purposes.Preferably, the base station includes processing capability and storagewhereby performance data can be assessed and processed. For example, auser at the end of the day can receive a print-out (or computer disk) ofhis performance data; and the report can include a comparison to otherperformers within the sporting activity. If the activity issnowboarding, for example, the user can see his performance data ascompared to other snowboarders on a particular mountain. Performancedata can also be catalogued according to age, date, and performance datatype (e.g., airtime, power, speed and/or drop distance).

In one aspect, the base station augments the sensing units by providingprocessing power to calculate and quantify the performance data. Forexample, in this aspect, raw sensor data such as from a microphone istransmitted from the sensing unit to the base station, which thereaftercalculates the appropriate performance data. The sensing unit “tags” thetransmitted data so as to identify a particular user. The base stationof this aspect then calculates and stores the appropriate performancedata for that particular user.

The base station can further include a Web Site server that connects thebase station to other such base stations via the Internet so thatperformance data from users can be collated, stored, compared and/orprinted for a variety of purposes. One or more servers thus function asthe primary servers from which users can obtain their performance datafrom their own computers, via the Internet (or via a LAN or WAN). In oneaspect, the primary servers also function as a gaming network whereperformance data from all users is integrated in a recreational manner,and made available to all or selected users.

In one aspect, sensing units (or sensing units and data units) arerented by the owners of a particular sporting area (e.g., a ski area)such as in connection with the rental of a snowboard, or even as astand-alone device that mounts to the user's board. The sensing unit canprovide real-time performance data to the user, via a connected displayor via a data unit. Alternatively, the sensing unit transmits data tothe rental facility (or to the base station connected via a LAN to therental facility) so that the user retrieves his or her performance dataat the end of the day.

In one aspect of the invention, performance data is sensed through oneor more sensors connected with the sensing unit. It is not desirable toprovide all performance data for all sporting activities. For example,for white water rafting or kayaking, a “power sensing unit” is useful—toquantify the roughness of the ride—but airtime data is practicallyuseless since typically such vehicles do not catch air. In addition, forany given system (i.e., sensing units or sensing units and data unitscombined), more sensors add cost and require added processingcapability, requiring more power draw and reducing battery lifetime.Therefore, certain aspects of the invention provide sensing units thatprovide only that portion of the performance data that is useful and/ordesirable for a given sporting function, such as the following sensingunits:

Airtime Sensing Unit

One sensing unit of the invention measures “air” time, i.e. the time aperson such as a snowboarder or skier is off the ground during a jump.This airtime sensing unit is preferably battery-powered and includes amicroprocessor (or microcontroller). The airtime sensing unit eitherconnects to a data unit; or can include a low-powered liquid crystaldisplay (LCD) to communicate the “air” time to the user. The componentsfor this airtime sensing unit can include one or more microphones oraccelerometers to detect vibration (i.e., caused by friction andscraping along the ground) of the user's vehicle along the ground, sothat “airtime” is measured when an appropriate absence of vibration isdetected. Preferably, the electronics for the airtime sensing unit areconveniently packaged within a single integrated circuit such as anASIC. A digital memory stores airtime data; or alternatively, theairtime sensing unit transmits airtime performance data to a data unitor to a base station.

The airtime sensing unit preferably provides several facets of airtimeperformance data, such as any of the following information data andfeatures:

(1) Total and peak air time for the day. In this aspect, the airtimesensing unit provides at least the peak airtime for the day. The sensingunit can also integrate all airtimes for the day to provide a totalairtime.

(2) Total dead time for the day. In this aspect, the airtime sensingunit includes an internal clock that also integrates the time for whichno sporting activity is made such as over a given day. For example, deadtime can include that time within which the user is at the bar, ratherthan skiing.

(3) Air time for any particular jump. As discussed above, briefly, thisaspect of the airtime sensing unit provides substantially real-time datato the user such as the amount of airtime for a recent jump. By way ofexample, a data unit with headphones, in one aspect, provide this datato the user immediately after the jump. Alternatively, the airtime datafor the jump is stored within memory (either within the data unit or inthe sensing unit) so that the user can retrieve the data at hisconvenience. For example, data for a particular jump can be retrievedfrom a watch data unit on the chairlift after a particular run whichincluded at least one jump. In this manner, the user can havesubstantially real-time feedback for the airtime event.

(4) Successive jump records of air time. In this aspect, jump recordsover a selected period (e.g., one day) are stored in memory either inthe data unit or in the airtime sensing unit. These airtime “records”are retrieved from the memory at the user's convenience. The system canalso store such records until the memory is full, at which time theoldest record is over-written to provide room for newer airtime data.The data can also be transmitted to a base station which includes itsown memory storage for retrieval by the user.

(5) Averages and totals, selectable by the user. In this aspect, thesensing unit or data unit (or the base station) saves airtime datawithin memory for later retrieval by the user. The period for which thedata is valid is preferably selectable by the user. The data of thisaspect includes airtime averages, over that period, or airtime totals,corresponding to the summation of those airtimes over that period.

(6) Rankings of records. In this aspect, the sensing unit or data unit(or base station) saves airtime data within memory for later retrievalby the user. For example, the user obtains airtime data through the dataunit while on the chairlift or later obtains the data in print-out format the base station, or a combination of the two. The period for whichthe data is valid is preferably selectable by the user. The data of thisaspect includes airtime records, over that period, and the airtimerecords are preferably ranked by airtime size, the biggest “air” to thesmallest.

(7) Logic to reject activities which represents false “air” time. Asdiscussed above, the preferred airtime sensing unit includes logiccircuitry to reject false data, such as standing in line. Typically, thelogic sets outer time limits on acceptable data, such as one half secondto five seconds for snowboarding, one quarter second to three secondsfor roller-blading, and user selected limits, targeted to a particularuser's interest or activity. The logic circuitry of the airtime sensingunit preferably also works with a speed sensor, as discussed herein; andthe logic operates to measure airtime only when the sensing unit ismoving above a minimum speed. For example, when the sensing unitincludes an airtime sensor and a speed sensor, the logic ensures thatairtime data is measured only if there is motion. Such logic thenensures that false data corresponding to standing in line is notrecorded as performance data. The speed limits tied to the logic arepreferably selectable by the user; though certain default speeds are setfor certain activities. For example, for skiing and snowboarding, 5 mphis a reasonable lower speed limit, such that all airtime, drop distanceand/or power measurements are ignored at lower speeds. Forroller-blading, the lower limit of speed is reasonably 1 mph, as forwind-surfing.

(8) Toggle to other device functionality. Although this sectiondescribes an airtime sensing unit, many sensing units of the inventionincorporate at least two sensors, such as: airtime sensor and speedsensor: airtime sensor and power sensor; airtime sensor and dropdistance sensor; a combination of airtime, power, and drop distancesensors; a combination of airtime, drop distance and speed sensors; acombination of airtime, power and speed sensors; and a full sensing unitof airtime, speed, power and drop distance sensors. Accordingly, atoggle button is usually included with the sensing unit (oralternatively with the data unit) such that the user can toggle to datacorresponding to the desired performance data. Similar toggle buttonscan be included with the sensing unit or data unit (which transmits datato the sensing unit) to activate only certain portions of the sensingunit, e.g., to turn off speed sensing. Alternatively, data from anygiven sensor can be acquired according to user-specified requirements.

Those skilled in the art should appreciate that a sensing unit withmultiple sensors can simply acquire all the data, and that the data issorted according to user needs and requests by toggle functionality atthe data unit or at the base station (i.e., such as entering a requestfor the desired information at the computer keyboard).

(9) User interface to control parameters. As discussed above, thesensing unit and/or data unit preferably include buttons or toggleswitches for the user to interact with the unit. For example, one of theunits should include an ON/OFF switch, and at least one button tocommand the display of performance data.

In other aspects, the airtime data of above paragraphs (1)-(6) can beshown on a display connected with the sensing unit, or they can betransmitted to an associated data unit, or to a base station.

Speed Sensing Unit

One sensing unit of the invention measures “speed.” This speed sensingunit is preferably battery-powered and includes a microprocessor (ormicrocontroller). The speed sensing unit either connects to a data unit;or can include a low-powered liquid crystal display (LCD) to communicatethe “speed” to the user. Certain sporting activities also benefit by themeasurement of speed, including skiing, snowboarding, mountain biking,wind-surfing, roller-blading, and others. To detect user motion, thesensing unit includes a speed sensor such as a Doppler module, asdescribed in U.S. Pat. Nos. 5,636,146, 4,722,222, and 4,757,714,incorporated herein by reference. Alternatively, the speed sensor caninclude a microphone subsystem that detects and bins (as a function offrequency) certain sound spectra; and this data is correlated to knownspeed frequency data. A speed sensor can also include a microphonewhich, when coupled with the controller subsystem, detects a “pitch” ofthe vehicle; and that pitch is used to determine speed to a definedaccuracy (typically at least 5 mph). The speed sensor can alternativelyinclude a Faraday effect sensor (which interacts a magnetic field withan electric field to create a voltage proportional to speed).Specifically, the Faraday effect sensor sets up a current that runsorthogonal to the speed direction. In one aspect, the current is createdbetween two electrodes formed by the two metal edges of a ski orsnowboard (in circuit with the snow). When the Faraday effect sensormoves, a voltage is created proportional to velocity. The magnetic fieldis formed by a magnet that creates a flux substantially perpendicular tothe current flow (those skilled in the art should appreciate that theorthogonality of the respective quantities can be compensated by a sinefunction if the quantities are not orthogonal, to retrieve the speeddata).

In another aspect, a sensing unit with a microphone, for example, canbenefit by using an electrical filter with a variable bandpass thattracks the dominant spectral content, denoted herein as a “trackingfilter.”

This speed sensing unit can be stand-alone, or a speed sensor can beintegrated into a sensing unit with multiple sensors, such as describedabove. For example, one speed sensing unit provides both “air” time andspeed to the user of the device.

Preferably, the electronics for the speed sensing unit are convenientlypackaged within a single integrated circuit such as an ASIC. A digitalmemory stores speed data; or alternatively, the speed sensing unittransmits speed performance data to a data unit or to the base station.

The speed sensing unit preferably provides several facets of speedperformance data, such as any of the following information data andfeatures:

(1) Average and peak speed for the day. In this aspect, the speedsensing unit provides at least the peak speed for the day. The sensingunit can also integrate all speeds for the day to provide an averagespeed.

(2) Speed for any particular period or run. This aspect of the speedsensing unit provides substantially real-time data to the user such asthe speed reached in a recent run. By way of example, a data unit withheadphones can provide this data immediately (e.g., continuallyinforming the user of data such as “25 mph” or “15 mph”). Alternatively,the speed data for the run or period is stored within memory (eitherwithin the data unit or in the sensing unit) so that the user canretrieve the data at his convenience. For example, data for a particularrun or period can be retrieved from a watch data unit on the chairliftafter a particular run. In this manner, the user can have substantiallyreal-time feedback for recent periods.

(3) Successive records of speed. In this aspect, peak or average speedrecords over a selected period (e.g., one day) are stored in memoryeither in the data unit or in the speed sensing unit. These speed“records” are retrieved from the memory at the user's convenience. Thesystem can also store such records until the memory is full, at whichtime the oldest record is over-written to provide room for newer speeddata. The data can also be transmitted to a base station which includesits own memory storage for retrieval by the user.

(4) Averages and totals, selectable by the user. In this aspect, thesensing unit or data unit (or the base station) saves speed data withinmemory for later retrieval by the user. The period for which the data isvalid is preferably selectable by the user. The data of this aspectpreferably includes speed averages over that period.

(5) Rankings of records. In this aspect, the sensing unit or data unit(or base station) saves speed data within memory for later retrieval bythe user. For example, the user obtains speed data through the data unitwhile on the chairlift or later obtains the data in print-out form atthe base station, or a combination of the two. The period for which thedata is valid is preferably selectable by the user. One record caninclude peak and/or average speed, over that period. The records arepreferably ranked by velocity, the fastest to the slowest speeds.

(6) Logic to reject data representing contaminated speed data. Thepreferred speed sensing unit includes logic circuitry to reject falsedata, such as data corresponding to two hundred miles per hour.Typically, therefore, the logic sets outer speed limits on acceptabledata, such as seventy miles per hour for a skier, as an upper limit, toone or five miles per hour as a lower limit (data that is slower thanthis rate is not, generally, of interest to skiers). Other reasonablelimits are 70 mph to 5 mph for snowboarding, and 40 mph to 5 mph forroller-blading. User selected limits can also be used within the speedsensing unit and targeted to a particular user's interest or activity.

(7) Toggle to other device functionality. Although this sectiondescribes a speed sensing unit, many sensing units of the inventionincorporate at least two sensors, such as: speed sensor and powersensor; speed sensor and drop distance sensor; and a combination ofspeed, power, and drop distance sensors. Accordingly, a toggle button isusually included with the speed sensing unit (or alternatively with thedata unit) such that the user can toggle to data corresponding to thedesired performance data. Similar toggle buttons can be included withthe sensing unit or data unit (which transmits data to the sensing unit)to activate only certain portions of the sensing unit, e.g., to turn offairtime or drop distance sensing. Alternatively, data from any givensensor can be acquired according to user-specified requirements.

(8) User interface to control parameters. As discussed above, the speedsensing unit and/or data unit preferably include buttons or toggleswitches for the user to interact with the unit. For example, one of theunits should include an ON/OFF switch, and at least one button tocommand the display of performance data.

In one aspect, a sensing unit with multiple sensors simply acquires allthe data, and that data is sorted according to user needs and requestsby toggle functionality at the data unit or at the base station (i.e.,such as entering a request for the desired information at the computerkeyboard).

Power Sensing Unit

One sensing unit of the invention measures “power”, a measure of theamount of energy absorbed or experienced by a user during a period suchas a day. The power sensing unit thus provides a measure of theintensity or how “hard” the user played during a particular activity.The components for this power distance sensing unit can include one ormore microphones or accelerometers to sense vibration or “jerk” of theuser or the user's vehicle relative to the ground. For example, onepower sensing unit provides a kayaker with the ability to assess andquantify the power or forces experienced during a white-water ride. Thepower sensing unit is preferably battery-powered and includes amicroprocessor (or microcontroller). In one aspect, “power” is measuredthrough an accelerometer. In another aspect, the power sensor includes amicrophone, as discussed below. As before, the power sensing unit isstand-alone, or it can be incorporated with other units discussedherein. Preferably, the electronics for the power sensing unit areconveniently packaged within a single integrated circuit such as anASIC. A digital memory stores power data; or alternatively, the powersensing unit transmits power performance data to a data unit. One powersensor according to the invention is an accelerometer, oriented in thedirection most indicative of expended energy (e.g., for skiing, theaccelerometer is preferably oriented perpendicular to the ski surface).Another power sensor is a microphone, preferably mounted within anenclosure which generates sound in response to user activity.

The power sensing unit preferably provides several facets of powerperformance data, such as any of the following information data andfeatures:

(1) Peak and average power for the day. In one aspect, a power sensor isan accelerometer which generates analog data that is digitally sampledby the controller subsystem at a rate such as 1000 Hz, 100 Hz or 10 Hz.This digitally sampled data is integrated over a “power period” such asone-half second, one second, five seconds, ten seconds, fifteen seconds,twenty seconds, thirty seconds, one minute, or five minutes (dependingon the sporting activity)—to specify a power “value”. In another aspect,a peak power is determined for power values over a given user-selectedperiod, e.g., one minute, one day, or other user-selected period, andstored within memory (in the sensing unit, in the data unit, and/or inthe base station) for subsequent retrieval by the user. The powersensing unit can also provide an average power value over that period.By way of example, for snowboarding, a user might experience very highpower activity over a period of fifteen seconds, such as within a mogulrun. By determining power values over one second intervals (i.e., the“power period”), the mogul run power activity will clearly stand out asa power event in subsequent data analysis. The power period can be userselected, such as over a run down a slope on a mountain. For example,snowboarders over a run down a slope can integrate power values overthat period to determine a total value, which can be compared amongstusers. Alternatively, the integrated value can be divided by the totalnumber of samples to determine an average power over that run.

(2) Successive power records. In this aspect, peak power records arestored in memory either in the data unit or in the power sensing unit.These power “records” are retrieved from the memory at the user'sconvenience. The system can also store such records until the memory isfull, at which time the oldest record is over-written to provide roomfor newer power data. The data can also be transmitted to a base stationwhich includes its own memory storage for retrieval by the user.

(3) Rankings of records. In this aspect, the power sensing unit or dataunit (or base station) saves power data within memory for laterretrieval by the user. For example, the user obtains power data throughthe data unit while on the chair-lift or later obtains the data inprint-out form at the base station, or a combination of the two. Theperiod for which the data is valid is preferably selectable by the user.The data of this aspect includes power records, over that period, andthe power records are preferably ranked by the largest to the smallest.

(4) Logic to ignore data that contaminates power data. By way ofexample, data from sensors such as accelerometers can provide noisespikes that correspond to unreasonable power values; and the logicoperates to delete such noise spikes.

(5) Toggle to other device functionality. Although this sectiondescribes a power sensing unit, many sensing units of the inventionincorporate at least two sensors, such as a power sensor and dropdistance sensor. Accordingly, a toggle button is usually included withthe sensing unit (or alternatively with the data unit) such that theuser can toggle to data corresponding to the desired performance data.Similar toggle buttons can be included with the sensing unit or dataunit (which transmits data to the sensing unit) to activate only certainportions of the sensing unit, e.g., to turn off drop distance sensing.Alternatively, data from any given sensor can be acquired according touser-specified requirements.

(6) User interface to control parameters. As discussed above, thesensing unit and/or data unit preferably include buttons or toggleswitches for the user to interact with the unit. For example, a sensingunit of one aspect includes an ON/OFF switch and at least one button tocommand the display of performance data. Since power can be scaled tocorrespond to real data, such as “g's” or “joules”, one button can beused to change the units of the power values.

Drop Distance Sensing Unit

One sensing unit of the invention measures “drop distance”. This dropdistance sensing unit is preferably battery-powered and includes amicroprocessor (or microcontroller). The drop distance sensing uniteither connects to a data unit; or can include a low-powered liquidcrystal display (LCD) to communicate the “drop distance” to the user.The components for a drop distance sensing unit of one aspect includes apressure sensor or altimeter. Preferably, the electronics for the dropdistance sensing unit are conveniently packaged within a singleintegrated circuit such as an ASIC. A digital memory unit stores dropdistance data; or alternatively, the drop distance sensing unittransmits drop distance performance data to a data unit.

The drop distance sensing unit preferably provides several facets ofdrop distance performance data, such as any of the following informationdata and features:

(1) Total and peak drop distance for the day. In this aspect, the dropdistance sensing unit provides at least the peak drop distance for theday. The sensing unit can also integrate all drop distances for the dayto provide a total drop distance.

(2) Drop distance for any particular jump. This aspect of the dropdistance sensing unit provides substantially real-time data to the usersuch as the drop distance for a recent jump. By way of example, in oneaspect, a data unit with headphones provides this data immediately afterthe jump. Alternatively, the drop distance data for the jump is storedwithin memory (either within the data unit or in the sensing unit) sothat the user can retrieve the data at his convenience. For example,data for a particular jump can be retrieved from a watch data unit onthe chairlift after a particular run which included at least one jump.In this manner, the user can have substantially real-time feedback forthe drop distance event.

(3) Successive jump records of drop distance. In this aspect, jumprecords over a selected period (e.g., one day) are stored in memoryeither in the data unit or in the drop distance sensing unit (or at thebase station). These drop distance “records” are retrieved from thememory at the user's convenience. The system can also store such recordsuntil the memory is full, at which time the oldest record isover-written to provide room for newer drop distance data. The data canalso be transmitted to a base station which includes its own memorystorage for retrieval by the user.

(4) Averages and totals, selectable by the user. In this aspect, thesensing unit or data unit (or the base station) saves drop distance datawithin memory for later retrieval by the user. The period for which thedata is valid is preferably selectable by the user. The data of thisaspect includes drop distance averages, over that period, or dropdistance time totals, corresponding to the summation of those dropdistances over that period.

(5) Rankings of records. In this aspect, the sensing unit or data unit(or base station) saves drop distance data within memory for laterretrieval by the user. For example, the user obtains drop distance datathrough the data unit while on the chair-lift or later obtains the datain print-out form at the base station, or a combination of the two. Theperiod for which the data is valid is preferably selectable by the user.The data of this aspect includes drop distance records, over thatperiod, and the drop distance records are preferably ranked by size, thelargest distance to the smallest.

(6) Logic to reject activities which represents false drop distance. Thepreferred drop distance sensing unit includes logic circuitry to rejectfalse data. Typically, the logic sets outer drop distance limits onacceptable data, such as three feet to one hundred feet for snowboardingand skiing (or up to 150 feet for extreme sports), and user selectedlimits, targeted to a particular user's interest. The logic circuitry ofthe drop distance sensing unit preferably also works with an airtimesensor, as discussed above; and the logic operates to measure dropdistance only when there is a detected airtime. For example, when thesensing unit includes an airtime sensor and a drop distance sensor, thelogic ensures that drop distance data is measured only if there is anairtime event, which can include its own logic as discussed above. Thelimits for other sports varies. In roller-blading, for example, the dropdistance limits can be set to one foot minimum to ten or fifteen feetmaximum.

(7) Toggle to other device functionality. Although this sectiondescribes a drop distance sensing unit, many sensing units of theinvention incorporate at least two sensors, such as: drop distancesensor and speed sensor; drop distance sensor and power sensor; dropdistance sensor and airtime sensor; and combinations. Accordingly, atoggle button is usually included with the sensing unit (oralternatively with the data unit) such that the user can toggle to datacorresponding to the desired performance data. Similar toggle buttonscan be included with the sensing unit or data unit (which transmits datato the sensing unit) to activate only certain portions of the sensingunit, e.g., to turn off speed sensing. Alternatively, data from anygiven sensor can be acquired according to user-specified requirements.

(8) User interface to control parameters. As discussed above, thesensing unit and/or data unit preferably include buttons or toggleswitches for the user to interact with the unit. For example, thesensing unit of one aspect includes an ON/OFF switch, and at least onebutton to command the display of performance data such as drop distance.

In one aspect, the invention incorporates a pair of power meters thatmeasure and quantify a competitor's performance during mogulcompetitions. In this application, one device is mounted to the ski (orlower body, such as the lower leg), and another to the upper body. An RFsignal unit communicates readings from both devices to a signalcontroller at the judge's table. The combined signals determine theforce differential between the lower legs and the upper body, giving anactual assessment of a competitor's performance. The device startstransmitting data at the starting gate. The device of this aspect canalso be coupled to the user via a data unit with headphones to provide ahum or pitch which tells the user how effective his/her approach is.

In another aspect, the invention provides a performance system whichgauges the negative airtime aspects of speed skiers. For example, it isundesirable for skiers such as Tommy Moe to lift off of the groundduring training, and certainly during a speed event, which slows theskier's speed. In this aspect, the system informs the user (in realtime, via a data unit) of instances of air time so that the skier canadjust and improve his competitive position. Airtime in this aspect isthus typically less than three seconds and can be as small as one tenthof a second or less. The data is preferably also communicated to a basestation so that the data can be replayed together with a video of therun, so that the skier can get feedback of airtime (unwanted in speedskiing) while watching his technique.

In another aspect, the invention provides a speed and airtime sensingunit such as described above, and additionally provides a height sensorintegrated with the sensing unit. In one aspect—identified herein as the“default” height measure—the height sensor detects speed and convertsthat speed data to height. Many jumps performed in sporting events suchas snowboarding occur off of a ledge, such that “height” is determinedsolely by the force of gravity. In one aspect, therefore, drop distanceheight is determined by ½at2, where a is the acceleration due to gravity(9.81 meters per second squared, at sea level) and where t is airtime,as determined by an airtime sensor as described herein. By way ofexample, for a one second airtime, a drop distance of 4.9 meters ismeasured. This result is approximately true even if the airtime occurson a slope down a mountain. However, this calculation will be in errorif there is an upward or downward motion at the start of the airtime.For example, if a jump occurs off of a mogul and the user is launchingupwards into the air, then this calculation will produce an incorrectnumber. Accordingly, the height sensor preferably includes a levelsensor which senses and measures the angle of motion relative to a planeperpendicular to the force of gravity. This angle determines thedistance which should be added or subtracted from the default measure.By way of example, if at the beginning of a two second airtime the usermoves at a speed of 10 mph (about 4.47 m/s), at an angle of 15 degreesupwards (such as off a mogul), then the velocity vector in the verticaldirection, Vv, is sin(15°)*10 mph; and the distance added to the defaultmeasure is approximately sin(15°)*2(Vv2)/a, or 1.05 m. The time for thisupward-traveled distance is sin(15°)*2Vv/a, or 0.24 s. The default timein this example is thus total airtime—0.24 s; and the default measure is15.2 m. The total drop distance is then 15.2 m plus 1.05 m, or 16.25 m.

In one aspect, the invention provides a system for determining the lofttime of a moving vehicle off of a surface. A loft sensor senses a firstcondition that is indicative of the vehicle leaving the surface, andfurther senses a second condition indicative of the vehicle returning tothe surface. A controller subsystem, e.g., typically including amicroprocessor or microcontroller, determines a loft time that is basedupon the first and second conditions, and the loft time is preferablydisplayed to a user of the system by a display, e.g., a LCD or LEDdisplay. In another aspect, a power module such as a battery is includedin the system to power the several components. In addition, a housingpreferably connects and protects the controller subsystem and the userinterface; and further includes an interface (possibly including velcro)that facilitates attaching the housing to the vehicle.

One preferred aspect of the invention includes a speed sensor, connectedto the controller subsystem, which senses a third condition that isindicative of a velocity of the vehicle (or at least indicates that thevehicle is in forward motion). In this aspect, the controller subsystemincludes means for converting the third condition to informationrepresentative of a speed of the vehicle. Alternatively, the speedsensor is used as logic for the airtime sensor to switch off thecollection of data when there is no forward motion. According to oneaspect, the system provides a user with airtime and speed of thevehicle.

In yet another aspect, a display of the invention displays selectiveinformation, including one or more of the following: the loft time; aspeed of the vehicle; a peak loft time; an average loft time; a totalloft time; a dead time; a real activity time; an average speed;successive records of loft information; successive records of speedinformation; a distance traveled by the vehicle; and a height achievedby the vehicle off of the surface.

In still another aspect, the invention includes a user interface forproviding external inputs to the sensing and/or data units, includingone or more of the following: a start/stop button for selectivelystarting and stopping the acquisition of data; a display-operate buttonfor activating the display selectively; a speed/loft/power/drop distancetoggle button for alternatively commanding a display of differentperformance data; means for commanding a display of successive recordsof performance data selectively; means for commanding a display ofinformation corresponding to average performance data; means forcommanding a display of dead time; means for commanding a display ofdistance traveled by the vehicle upon which the user rides; means forcommanding a display of height achieved by the vehicle off of thesurface; and means for commanding a display of real activity time.

Preferably, the controller subsystem of the invention includes a clockelement, e.g., a 24-hour clock, for providing information convertible toan elapsed time. Accordingly, the subsystem can perform variouscalculations, e.g., dead time, on the data acquired for display to auser. The clock can also be incorporated into a data unit, as a matterof design choice.

In another aspect, the airtime sensor is constructed with one of thefollowing technologies: (i) an accelerometer that senses a vibrationalspectrum; (ii) a microphone that senses a noise spectrum; (iii) a switchthat is responsive to a weight of a user of the vehicle; (iv) avoltage-resistance sensor that generates a voltage indicative of a speedof the vehicle; and (v) a plurality of accelerometers connected forevaluating a speed of the vehicle.

In another aspect, induced-strain sensors, such as a piezoceramics(e.g., PZT, or lead zirconate), piezopolymer (e.g., PVDF), or shapememory (e.g., NiTiNOL) elements can be used in sensors discussed herein.An “induced strain” sensor provides a measurable output such as avoltage in response to an applied strain, generally a compressivestrain. Also, strain gages and load cells (which are usually made usingstrain gage bridges) can also be incorporated into sensors herein: theformer for measuring bending strains, the latter for forces andcompressive strains. In still another aspect, FSRs (force sensingresistors), such as those manufactured by IEE Interlink, can be used.The FSRs are pads consisting of inter-digitated electrodes over asemi-conductive polymer ink, wherein the resistance between theelectrodes decreases nonlinearly as a function of applied compressiveload, with high sensitivity and low cost.

In a preferred aspect, the airtime sensor of the invention senses aspectrum of information, e.g., a vibrational or sound spectrum, and thecontroller subsystem determines the first and second conditions relativeto a change in the spectrum of information. Further, the controllersubsystem interprets the change in the spectrum to determine the lofttime.

For example, one aspect of an airtime sensor according to the inventionincludes one or more accelerometers that generate a vibrational spectrumof the vehicle. In such an aspect, the first and second conditionscorrespond to a change in the vibrational spectrum. By way of anotherexample, one airtime sensor of the invention includes a microphonesubassembly that generates voltages corresponding to a noise spectrum ofthe vehicle; and, in this aspect, the first and second conditionscorrespond to a change in the detected noise spectrum. Because thesespectrums are influenced by the particular activity of a user, e.g.,standing in a ski line, a controller subsystem of the inventionpreferably includes logic for assessing boundary conditions of thespectrum and for excluding certain conditions from the determination ofairtime. Accordingly, if a skier is in a lift line, such conditions areeffectively ignored. One boundary condition, therefore, according to anaspect of the invention, includes an elapsed time between the firstcondition and the second condition that is less than approximately 500ms; such that events that are within this boundary condition areexcluded from the determination of airtime. One other boundarycondition, in another aspect, includes an elapsed time between the firstcondition and the second condition that is greater than approximatelyfive seconds; such that events that are outside this boundary conditionare excluded from the determination of airtime. Because these boundaryconditions are important in the aspects of the invention which utilize aspectrum of information, the sensing and/or data units preferablyutilize a user interface to provide selective external inputs to thecontroller subsystem and for adjusting the boundary conditionsselectively.

In one aspect, the change in a vibration or sound spectrum is detectedthrough waveform “enveloping” of the time domain signal, and then bypassing the output of this envelop to a threshold-measuring circuit.Pre-filtering of the signal, especially to remove low-frequency contentbeyond high pass filtering, can also be included.

In still another aspect, the controller subsystem determines a pitch ofthe spectrum by isolating a best-fit sine wave to a primary frequency ofat least part of the spectrum and by correlating the pitch to a vehiclespeed. Accordingly, the invention of this aspect detects spectruminformation and correlates that information to a speed of the vehicle.Typically, a higher pitch frequency corresponds to a higher vehiclespeed and a lower pitch frequency corresponds to a lower vehicle speed.However, in another aspect, the selected pitch frequency is calibratedrelative to a selected vehicle and speed.

In still another aspect, speed is inferred by the amount of energy atdifferent vibrational frequencies, as discussed herein.

The invention also provides, in another aspect, means for storinginformation including look-up tables with pitch-to-speed conversions fora plurality of vehicles. This is useful because different vehicles havedifferent associated noise and/or sound spectrums associated with thevehicle. Accordingly, the invention in this aspect includes memory forstoring the respective calibration information of the different vehicles(typically in a look-up table format) so that a user can utilize theinvention on different vehicles and still accurately determine speed.Specifically, a particular pitch is associated with a particular speedfor a particular vehicle; and that association is selectively made bythe user.

In several aspects of the invention, the controller subsystem includesone or more of the following: means for selectively starting andstopping the acquisition of data by the sensing unit; means forresponding to an external request to activate a display for the displayof performance data; means for responding to an external request toalternatively display airtime, drop distance, speed and/or power; and/ormeans for responding to an external request to display successiverecords of performance data.

The invention also provides certain methodologies. For example, in oneaspect, the invention provides a method for determining the loft time ofa moving vehicle off of a surface, comprising the steps of: (1) sensingthe vehicle leaving the surface at a first time; (2) sensing the vehiclereturning to the surface at a second time; and (3) determining a lofttime from the first and second times. Preferably, the loft time isprovided to the user who performed the jump via one of the followingmethods: through a display located with the user, either in a data unitor within a sensing unit; through a real time feedback heads-up displayor headphones; through a report available at a base station located atthe area where the jump occurred, such as after a day of skiing; and/orthrough a computer linked to a network like the Internet, where theairtime data is stored on a server on the network, such as a serverlocated at the area where the jump occurred.

In still another aspect, the invention provides a method of measuringthe amount of “power” a user absorbs during the day. A motion sensor,e.g., a microphone or accelerometer, attaches to the vehicle, preferablypointing perpendicular to the top of the vehicle (e.g., perpendicular tothe top surface of the snowboard) so that a measure of acceleration,“force”, jerk or jar associated with the user is made. The data from themotion sensor is integrated over a selected time—e.g., over the time ofthe skiing day, or over power periods such as one minute intervals—sothat an integrated measure of motion is acquired. By way of example, ifthe motion sensor is an accelerometer positioned with a sensitive axisarranged perpendicular to the top snowboard surface, then, throughintegration over the power period, an integrated measure of “power” isobtained.

Those skilled in the art should appreciate that power can be convertedto actual power or similar units—e.g., watts or joules or ergs orNewtons—though real units are not as important as having a constant,calibrated measure of “power” for each user. That is, suppose twosnowboarders have power sensors on their respective snowboards. If oneperson skis a green slope and another skis a double-diamond, then theintegrated value out of the double-diamond snowboarder will be greater.The units are therefore set to a reasonably useful value, e.g., genericpower “UNITS”. In one aspect, the power units are set such that a valueof “100” indicates a typical snowboarder who skies eight hours per dayand on maximum difficult terrain. At the same time, a snowboarder whorides nothing but green beginner slopes, all day, achieves something farless, e.g., a value of “1”. In this manner, average skiers on blue,intermediate slops will achieve intermediate values, e.g., “20” to “50”.Other scales and units are of course within the scope of the invention,and should be set to the particular activity.

Units for airtime are preferably set to seconds, such as “1.2 s”. Unitsfor speed are preferably set to miles per hour, kilometers per hour,meters per second, feet per second, inches per second, or centimetersper second. Units for drop distance are preferably set to feet, meters,inches, or centimeters.

In one aspect, the sensing unit (and/or the data unit) has a userinterface. The interface can include a display and/or audible feedbacksuch as through headphones In one aspect, the audible feedback informsthe user of big “air” words such as “awesome” if for example asnowboarder hit really big air (e.g., over five seconds). In anotheraspect, the interface electronics include a low-power piezo “buzzer” orheadphone “bud” speaker that sounds whenever an “air” condition issensed. This provides immediate feedback to the user. Further, inanother aspect a varying pitch is used to give a speed indication. Forinstance, the ear can readily distinguish an octave pitch change, whichcan for example correspond to each 5 mph change in speed.

The measure of power according to the invention thus providessignificant usefulness in comparing how strenuous one user's activity isas compared to another. For example, suppose two users ski only blue,intermediate slopes with the exact same skill and aggressiveness exceptthat one user chooses to sit in the bar for three hours having a coupleof cocktails. At the end of an eight hour day—providing the power periodis set for the whole day—the skier who skied all eight hours will have apower measurement that is 8/5 that of his cocktail-drinking companion.They can thereafter quantitatively talk about how easy or how difficulttheir ski day was. As for another example, suppose a third friend skisonly double-diamond slopes and he takes four hours out to drink beer. Atthe end of the day, his power measure may still be greater than hisfriends depending upon how hard he skied during his active time. Hecould therefore boast—with quantitative power data to back him up—thathe had more exercise than either of his friends even though he wasdrinking half the day.

In one aspect, the invention incorporates a breathalyzer—used to measurea user's consumption (i.e., a blood alcohol level)—and the level isstored such as within the memory within the controller subsystem. A basestation can upload the data to the memory, as desired.

The measure of air time, according to the invention, can also be used ina negative sense. That is, speed skiers try to maintain contact with theground as air time decreases their speed. By monitoring their air timewith the invention, they are better able to assess their maneuversthrough certain terrain so as to better maintain ground contact, therebyincreasing their speed.

The measurement of air, speed and power, and drop distance, in accordwith the invention, are preferably made through one or more sensorslocated with the vehicle, e.g., on the snowboard or ski, upon which theperson rides. As such, it is difficult to see the sensor; so one aspectthe invention provides an RF transmitter in the sensing unit. A dataunit coupled to the RF transmitter—e.g., in the form of a watch, pagingunit, or radio receiver with headphones, is located at a convenientlocation with the person. The performance data—e.g., air, power, dropdistance and speed—is transmitted to the person for convenient viewing,or listening. In still other aspects, a memory element in the data unit(or alternatively in the sensing unit) provides for storing selectedparameters such as successive records of speed, air, drop distance andpower, or averages for the performance data. Data can also betransmitted from the sensing unit to a base station, as discussed above.Those skilled in the art should appreciate that other data transfertechniques can be used instead of RF, including IR data transfer betweenthe units.

In one aspect, the sensing unit internally resets (i.e., shuts off) whenthe unit senses no reasonable or useful performance data for apreselected period of time. By way of example, through a clock withinthe microprocessor, the unit automatic time-outs after that period,saving battery power.

In one aspect, a temperature sensor is included with the sensing unit(or data unit). A temperature profile is taken over the course of aactivity day and is later displayed so that the user may boast that heor she skied in the most arduous situations.

Preferably, performance data is accumulated and then transmitted to abase station such as a ski lodge. For mountain biking, data can betelemetered back to a club house. Through the use of Internetconnectivity, these data sets can also be downloaded off a Web site sothat the user can compare different slopes or areas, together withperformance. The data can also be evaluated and figures of merit can beapplied to each run so that a skier can look at his or her performanceand see how they did relative to other users. A skier may find forexample that he skied better on that trail than any one else all month,year or ever. A handicap can also be applied to other mountains andtrails so that a national or world competition is achieved. Thisinterconnectivity is permitted by use of the World Wide Web or simply byusing bulletin boards that are called up and updated, as known in theart. Telenet or FTP sites can also contact each other or be contacted bya home site that will assimilate the data and prepare it for display.Security could be ensured so that a user has confidence that only he orshe can access their own data.

The invention thus provides, in one aspect, a national or regional gameto be played so that the many users can compare and store performancedata. Ski areas may use this data, for example, with the participant'sknowledge and consent so that it will lure skiers to their lifts in thehope that they will win an award. Awards for the highest vertical drop,most air time, greatest speed or most power may also be awarded. Theprizes could simply be free lift tickets.

In one aspect, power for the sensing units (or data units) may be savedduring times of inactivity by powering off most of the electronics witha solid state switch such as a MOSFET. The processor or some minimumelectronics can remain powered so that when activity is detected, theremaining electronics are powered as needed. Further, to save power,sensors such as accelerometers are duty cycled.

In another aspect, downward velocity is determined by knowing the rateof descent such as through a pressure sensor. Pressure sensing andairtime can thus be used to determine vertical drop, where loft isdetermined by the absence of a vibratory noise floor, for example.

In another aspect, the GPS is used to determine speed down a slope. Withupdates as frequent as one second, there is more than enough bandwidthto acquire changing GPS data. GPS however can have large errorsassociated with uncertainty of positioning calculations. This may beremedied by using differential GPS. Differential GPS makes use of afixed GPS receiver with a known position, such as at the base station.When functioning as a sensor, therefore, the GPS receiver receivesupdates from the base station to maintain accurate position. When largeerrors are received, they are rejected because the fixed receiver is ata known position, resulting in a data correction that is also applied tothe moving receiver on the slope. In some areas of the United States,the correction codes for differential GPS are broadcast for general use.

In still another aspect, when using a GPS receiver, individual ski mapsfor each trail are downloaded into memory so that the skier may seewhere they are on the display. Also, 3D topographical information isalso preferably downloaded so that features can be attached to thesemaps and to aid in performance data determination. By knowing the heightin 3D space of the receiver, and with the stored height of the slope inmemory, the distance off the ground is determined. Loft time is alsothus determined in addition to vertical drop. Loft detection with a GPSsystem may thus return the value of drop distance.

In another aspect, speed is determined by use of neural networksynthesis. A neural network extracts speed information from a sensorsuch as a microphone or an accelerometer. This is accomplished, forexample, by recording microphone data on a ski or snowboard along with atrue speed sensor, such as a Doppler microwave sensor. Two data sets arethus generated: the first data set contains data acquired from themicrophone that will be used in the final system; and the second dataset corresponds to the true device that is used as a reliable speeddetector. These two data sets are fed into a neural network, and theoutput of the neural filter is then compared with known good speed data.The various weights of the neural network are adjusted until a match isdetermined. At this point, the neural network is used to process thefirst data set to reliably determine speed. In the event that a match isnot found, a more complex but powerful network is developed. The firstdata set is then fed into the new net and a match is developed byadjusting the weights of the nodes. This process is repeated constantlyuntil a match is determined. Each failure results in a larger neuralnetwork but increases the probability that the next filter will achievea match.

In areas where the ski run is visible, the speed and trajectory of askier may be achieved by the use of a digital imaging system, in accordwith another aspect. The imaging system can thus include a CCD camerathat looks at the slope and watches skiers traverse down the slope. Byknowing the distances along the slope, and the fact that the camera isstationary, the distance moved is determined frame to frame,corresponding to position in time that correlates to speed. Skiers canbe identified by signs they wear, including a distinctive pattern whichallows identification of individual skiers.

The invention is next described further in connection with preferredembodiments, and it will be apparent that various additions,subtractions, and modifications can be made by those skilled in the artwithout departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the invention may be obtained byreference to the drawings, in which:

FIGS. 1A and 1B show a schematic layout of a sensing unit, data unit andbase station, each constructed according to the invention, for providingperformance data to participants in sporting activities;

FIGS. 2, 3, 4 and 5 illustrative certain operational uses of the unitsof FIG. 1;

FIG. 6 graphically illustrates actual vibration data taken during a skijump with an airtime sensor utilizing an accelerometer, in accord withthe invention;

FIGS. 6A and 6B represent processed versions of the data of FIG. 6;

FIG. 7 schematically illustrates a controller subsystem constructedaccording to the invention and which is suitable for use in the sensingunit of FIG. 1;

FIG. 8 illustrates one exemplary pitch-detection process, in accord withthe invention, which is used to determine speed;

FIG. 9 schematically illustrates process methodology of converting aplurality of acceleration values to speed, in accord with the invention;

FIG. 10 schematically illustrates process methodology of calculatingspeed, direction, and/or vehicle drop distance, in accord with theinvention, by utilizing accelerometer-based sensors;

FIG. 11 illustrates methodology for measuring drop distance, speedand/or airtime, in accord with the invention, by utilizing a Dopplermodule as a drop distance, speed, and/or airtime sensor;

FIG. 12 illustrates an improvement to a snowboard, in accord with theinvention;

FIGS. 13 and 14 show top and side cross-sectional views, respectively,of a speed sensor of the invention, coupled to a snowboard, fordetermining speed by utilizing charge cookies; and FIG. 15 shows aschematic diagram for processing the speed sensor of FIGS. 13 and 14;

FIGS. 16 and 17 show top and side views, respectively, of anotherembodiment of a speed sensor, according to the invention, coupled to asnowboard and utilizing magnetic cookies to determine speed;

FIGS. 18 and 19 show top and side cross-sectional views, respectively,of another embodiment of a speed sensor, according to the invention,coupled to a snowboard and utilizing optical windows to determine speed;

FIG. 20 shows a schematic perspective view—not to scale—of a skierengaged in competition on a mogul course and of a system, constructedaccording to the invention, for monitoring two power values toquantitatively measure mogul skiing performance;

FIG. 21 schematically illustrates one system including a power sensingunit constructed according to the invention for measuring activityenergy for various sportsmen;

FIGS. 22-24 illustrate various, exemplary signals obtainable through thesystem of FIG. 21;

FIG. 25 illustrates an alternative airtime, speed and/or drop distancemeasuring system, according to the invention, utilizing a GPS receiver;

FIG. 26 schematically shows one airtime and/or power sensing unit of theinvention, mounted to a snowboard;

FIG. 27 schematically illustrates a performance system utilizing a dataunit in the form of a watch;

FIG. 28 illustrates a GPS-based drop distance sensing unit of theinvention;

FIG. 29 shows further detail of the unit of FIG. 28;

FIGS. 30-33, 34A, 34B and 35 illustrate data collection hardware used toreliably collect large quantities of sensor data at a remote andenvironmentally difficult location, in accord with the invention;

FIG. 36 shows a schematic view of a pressure-based drop distance sensingunit of the invention;

FIG. 37 illustrates further processing detail of the unit of FIG. 36;

FIG. 38 illustrates a power watch constructed according to theinvention;

FIG. 39 shows another power watch configuration, in accord with theinvention;

FIG. 40 shows a schematic view of a power/pressure system according tothe invention;

FIG. 41 illustrates a two-microphone speed sensing system of theinvention;

FIG. 42 illustrates process methodology for determining drop distanceduring airtime, in accord with the invention;

FIGS. 43 and 44 show real accelerometer data from a ski traveling at <2mph and >15 mph, respectively, in accord with the invention;

FIG. 45 illustrates one system for interpreting spectral data such asvibration to decipher airtime, power and speed, in accord with theinvention;

FIG. 46 illustrates use of a DSP to determine power in accord with theteachings of the invention;

FIG. 47 illustrates a GPS-based system of the invention;

FIG. 48 illustrates a neural network of the invention;

FIG. 49 illustrates methodology for a two sensor speed sensing unit ofthe invention; and FIGS. 50-51 show representative spectra from the twosensors;

FIGS. 52-53 show illustrative correlation functions;

FIG. 54 illustrates a bending wave within a ski which can be used forpower sensing, in accord with the invention;

FIG. 55 shows a two-sensor speed system constructed according to theinvention;

FIG. 56 shows a multi-sensor speed system constructed according to theinvention;

FIG. 57 shows a two-dimensional sensor speed system constructedaccording to the invention;

FIG. 58 and FIG. 59 show a Doppler-based system constructed according tothe invention;

FIG. 60 shows a force measuring system of the invention; and FIGS. 61-62show alternative systems;

FIGS. 63-73 illustrate force sensing techniques and issues, in accordwith the invention;

FIG. 74 shows a network game constructed according to the invention; andFIG. 75 describes further features of the game of FIG. 74;

FIG. 76 shows a boot-binding sensor arrangement constructed according tothe invention;

FIG. 77 shows a boot sensor arrangement constructed according to theinvention;

FIG. 78 illustrates data signals representative of sensing power inaccord with the invention;

FIG. 79 illustrates a Doppler sensing system constructed according tothe invention;

FIG. 80 illustrates a watch-based sensing system constructed accordingto the invention;

FIG. 81 illustrates a clothing-integrated sensor constructed accordingto the invention;

FIG. 82 shows a flow-chart illustrating drop distance logic in accordwith the invention;

FIG. 83 shows a real-time performance system constructed according tothe invention; and

FIGS. 84A-84H illustrate integration of a sensing unit of the inventionintegrated into various implements, in accord with the invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

FIG. 1A illustrates a sensing unit 10 constructed according to theinvention. A controller subsystem 12 controls the unit 10 and isconnected to one or more sensors 14 a-14 d. Typically, the subsystem 12receives data from the sensors 14 a-d through data line 16 a-d; thoughcertain sensors 14 require or permit control signals, so data lines 16a-d are preferably bi-directional. It is not necessary that the unit 10incorporate all sensors 14 a-14 d and only one of the sensors 14 a, 14b, 14 c or 14 d is required so as to provide performance data. In onepreferred embodiment, however, the unit 10 includes all four sensors 14a-14 d. In another preferred embodiment, only the airtime sensor 14 b isincluded within the unit 10.

The sensors 14 a-14 d take a variety of forms, as discussed herein.Generally, the speed sensor 14 a provides data indicative of speed tothe controller subsystem 12 along data line 16 a. One exemplary speedsensor 14 a utilizes a microwave Doppler module such as made by C&KElectronics. The airtime sensor 14 b provides data indicative of airtimeto the controller subsystem 12 along data line 16 b. One exemplaryairtime sensor 14 b utilizes a microphone such as a piezo foil by AMPSensors, Inc. The drop distance sensor 14 c provides data indicative ofdrop distance to the controller subsystem 12 along data line 16 c. Oneexemplary drop distance sensor 14 c utilizes a surface mount altimetersuch as made by Sensym, Inc. The power sensor 14 d provides dataindicative of power to the controller subsystem 12 along data line 16 d.One exemplary power sensor 14 d utilizes an accelerometer such as madeby AMP Sensors, Inc. or Analog Devices, Inc.

In certain embodiments, one sensor 14 functions to provide data that issufficient for two or more sensors 14. By way of example, in oneembodiment, the airtime sensor 14 b incorporates a microphone orpiezo-foil which senses noise vibration of the unit 10. This noisevibration data is used to sense motion (and/or coarse speed) and power;and thus a single sensor 14 b functions to provide data for sensors 14 aand 14 d. Those skilled in the art should thus appreciate that thenumber of sensors 14 is variable depending upon the type of sensingtransducer and upon the processing capability of the subsystem 12 (e.g.,a DSP chip within the subsystem 12 can provide flexible processing ofdata from the sensors 14 to limit the number of sensors 14 required toprovide performance data); and that the number of sensors 14 is made forillustrative purposes.

The controller subsystem 12 preferably includes a microprocessor ormicrocontroller 12 a to process data from the sensors 14 and to provideoverall control of the unit 10. The microprocessor 12 a can include a 24hr. clock to provide certain performance data features as describedherein. The subsystem 12 also preferably includes digital memory 12 b tostore parameters used to process data from the sensors 14 and to storeperformance data for later retrieval. The subsystem 12 also preferablyincludes logic 12 c to restrict data from the sensors 14 to reasonabledata compatible with certain limits such as stored within memory 12 b.For example, the memory 12 b can store speed limits for the speed sensor14 a, and the logic 12 c operates such that any data received from dataline 16 a is ignored if above or below a pre-set range (typically, oneto five seconds for sport activities such as snowboarding).

Those skilled in the art should appreciate that alternate configurationsof memory 12 b and logic 12 c are possible. By way of example, theseelements 12 b and 12 c can be incorporated entirely within themicroprocessor 12 a; and thus the configuration of the subsystem 12 isillustrative and not limiting. In addition, in certain embodiments ofthe invention as described herein, memory 12 b and/or logic 12 c are notrequired, since relatively raw data is acquired by the unit 10 andtransmitted “off board” through an optional remote data transmit section22 (e.g., an RF transmitter) and to a data unit 50 or to a base station70, as shown in FIG. 1B. In such embodiments, the raw data is processedwithin the data unit 50 or the base station 70 so that a user of theunit 10 can obtain performance data from the data unit 50 and/or basestation 70.

To acquire signals from the sensors 14, the controller subsystem 12typically includes A/D converters 12 d, such as known in the art. Eachsensor 14 also typically includes a preamplifier 20 which amplifies thesignal from the transducer within the sensor 14 prior to transmissionalong the associated data line 16. Those skilled in the art shouldhowever appreciate that the exact configuration of the preamplifier 20,microprocessor 12 a and the A/D converters 12 d depend upon specifics ofthe sensor 14 and the subsystem 12. For example, certain sensors 14available in the marketplace—such as an accelerometer subsystem—includepre-amplification and A/D conversion; so the data line 16 and subsystem12 associated with such a sensor should support digital transmissionwithout redundant A/D conversion.

In one embodiment, the sensing unit 10 is “stand alone” and thusincludes a user interface 24 that connects to the controller subsystem12 via a data line 26. The interface 24 includes an ON/OFF switch 24 a,to manually turn the unit 100N and OFF, and one or more buttons 24 b(preferably including at least one toggle button to other unitfunctionality) to command various actions of the unit 10, e.g., thedisplay of different performance data on the display 24 c. Those skilledin the art should appreciate that the interface 24 is illustrative,rather than limiting, and that elements such as the display 24 c canreside in other areas of the unit 10. The data line 26 is preferablybi-directional so that user commands at the interface 24 are recognizedand implemented by the subsystem 12 and so that performance data storedin the memory 12 b is displayed, upon command, at the display 24 c.

A battery 30 is generally used to power the unit 10, including the userinterface 24, controller subsystem 12 and sensors 14, if power isrequired. As such, back-plane power lines 30 a are shown to connect thebattery 30 to the various elements 24, 12, 14. One preferred sensorhowever is a piezo-foil that does not require power, and thus such aconnection 30 a may not be required for a sensor with a foil (note thatthe preamplifier 20 may still require power).

The unit 10 is generally enclosed by an appropriate housing 32, such asa plastic injected molded housing known in the art. The housing 32 isrugged to withstand the elements such as snow, water and dirt. Awater-tight access port 32 a permits for the removal and replacement ofthe battery 30 within the housing 32, as required, and as known in theart.

When the unit 10 is stand alone, the housing 32 also includes a window32 b (possibly the surface of the display 24 c integrated substantiallyflush with the housing surface) in order to see the display 24 c. Whenstand alone, the housing 32 also includes access 32 c to the buttons 24a, 24 b. The access 32 c is for example provided through pliant rubbercoverings; or the buttons 24 a, 24 b are made as keypads, as known inthe art, that integrate directly with the surface of the housing 32.Other techniques are available; and in each case the buttons 24 b, 24 aand housing 32 cooperate so as to provide an environmentally secureenclosure for the electronics such as the microprocessor 12 a whileproviding an operable interface to communicate with the subsystem 12.

The housing 32 preferably includes a universal interface 32 d whichprovides flexible and conformal mounting to a variety of surfaces, suchas to the relatively flat surface of a snowboard or to a round bar on amountain bike. The universal interface 32 d is designed to permit standalone units 10 to be sold in stores regardless of how or where a usermounts the unit, to determine performance data for his or her particularactivity.

In certain aspects, the sensing unit 10 is not “stand alone.” Inparticular, it is sometimes desirable to mount the sensing unit 10 in anobscure location that is hard to see and reach, such as on a ski, orwith a binding for a ski or snowboarding boot. In such locations, it ispreferable that the unit 10 is a “black box” that is rugged to withstandabuse and environmental conditions such as water, snow and ice.Therefore, in such a configuration, the user interface 24 is notincluded within the unit 10 (since snow and dirt can cover the unit 10),but rather data from the unit 10 is communicated “off board” such as tothe data unit 50. In this configuration, a data transmit section 22receives data from the subsystem 12 via data bus 23; and transmits thedata to a remote receiver, e.g., the data receive section 56 of the dataunit 50 and/or to the data receive unit 72 of the base station 70.

The communication between unit 10 and the data unit 50, or base station70, is preferably via RF signals 45, known in the art, which utilizeantennas 25, 58 and 78. However, those skilled in the art shouldappreciate that other data communication techniques are available,including infrared transmission, inductively coupled data transmission,and similar remote (i.e., non-wired) techniques. The data transmitsection 22 and antennas 25, 58 and 78 are thus shown illustratively,whereas those skilled in the art should appreciate that other techniquescan replace such elements, as desired, to perform the same function.

FIG. 1B thus also shows a schematic view of a data unit 50 constructedaccording to the invention. As mentioned above, the data unit 50cooperates with the unit 10 to provide performance data to a user of theunit 10. In one preferred embodiment, the unit 50 is sized and shapedmuch like a portable beeper, known in the art, and can include a display52 to inform the user of performance data. In another preferredembodiment, the unit 50 is incorporated within a watch such as providedby manufacturers like TIMEX™ or CASIO™. A battery 30′ provides power tothe elements of the unit 50 through power lines 30 a′ (in the watchconfiguration, the existing battery replaces battery 30′). A userinterface 24′ operates as described above (with like numerals) to, forexample, provide a display of performance data, upon command. The unit50 includes a housing 54 that is also preferably plastic injected moldedand rugged to protect the elements of the unit 50. Although notillustrated, the housing 54 incorporates access ports and windows, asknown in the art, to permit access to the buttons 24 b′ (preferablyincluding at least one toggle button to other unit functionality), toview the display 24 a′ (as similarly described in connection with thesensing unit 10), and/or to replace the battery 30′. The antenna 58represents one technique through which data 45 is communicated betweenthe units 10, 50; although those skilled in the art should appreciatethat other communication forms are within the scope of the invention,including communication by infrared light.

The data unit 50 generally requires a controller such as amicroprocessor 53 to control the unit 50 and the elements therein. Databuses 55 provide data interface by and between the microprocessor 53 andthe elements. Accordingly, data entered at the user interface 24′ isbidirectional through data bus 55 so that user commands are received andimplemented by the microprocessor 53. A memory 50 b is typicallyincluded within the data unit 50 (or within the processor 53) so as tostore parameters and/or performance data, much like the memory 12 b.

In a preferred embodiment, performance data is thus made available to auser via the display 52. However, in another embodiment, performancedata is transmitted to a headphones assembly 60 connected, datawise, tothe microprocessor 53 so that performance data is relayed in near realtime, as the user performs the associated stunt. The headphones 60connect to the unit 50 by standard wiring 62 and into a jack 64 in theunit 50. For example, through the user interface 24′, the user cancommand the microprocessor 53 to provide airtime data to the headphones60 immediately after an airtime is detected. Other performance data cansimilarly be set, such as continual speed playback, through theheadphones 60.

Performance data can thus be viewed on the display 52 and/or “heard”with the headphones assembly 60. In either case, a user commands theunit 50 to provide performance data for any memory stored within memory12 b or 50 b. Accordingly, data communication between the units 10 and50 is preferably bi-directional, so that a user's command at interface24′ is understood and implemented by the processor 12 a.

Those skilled in the art should appreciate that the microprocessor 53need not be a complex or expensive microprocessor as the majority of theprocessing for performance data is done within the sensing unit 10. Assuch, the microprocessor 53 can be a microcontroller which operates withbasic functionality, e.g., to display performance data corresponding touser inputs at the interface 24′. How processing is apportioned betweenthe units 50, 10 is, however, a matter of design choice. That is, forexample, most of the processing can be done within the unit 50, whereinthe unit 10 can then have reduced processing capability, if desired.These choices extend to elements such as the memories 12 b, 50 b, asthey can have redundant capability. When the unit 10 is stand alone, auser interface 24 is generally included (unless data is transmitteddirectly to the base station 70 for later retrieval). When the system ofthe invention includes both units 10, 50, then the user interface 24 isgenerally not included since the interface 24′ sufficiently controls thesystem. In this latter case, the functionality and configuration of themicroprocessors 12 a, 53, memory 12 b, 50 b and logic 12 c are a matterof design choice; and some elements might be eliminated to save cost.For example, the memory 50 b can be designed to support all memoryrequirements of a system incorporating both units 10, 50 to eliminateredundancy; and thus memory 12 b would not be required.

Other configurations of a system combining units 10 and 50 exist. Forexample, one configuration eliminates the display 52 so that performancedata is only available via the headphones assembly 60. In anotherconfiguration, the sensing unit 10 works only with the base station 70and without a data unit 50. Further, such a configuration need notinclude a user interface 24 or a display 24 c, since all data collectedby the unit 10 can be stored and processed at the base station 70.

The base station 70 thus includes an antenna 78 and a data receive unit72 (or alternatively other wireless communication technology, as knownin the art) to collect data signals 45. Typically, the base station 70corresponds to a well known facility located at the sporting area, suchas a ski lodge. A base station computer 74 connects to the base stationdata receiver unit 72, via the bus 76, to collect and process data. Assuch, one sensing unit 10 of the invention simply includes one or moresensors 14 and enough control logic and processing capability totransmit data signals 45 to the base station 70, so that substantiallyall processing is done at the base station 70. This configuration isparticularly useful for aspects of the invention such as speed skiing,where the sensing unit 10 is mounted with the speed skier's ski, butwhere that user has no requirement to view the data until later, afterthe run (or where instructors or judges primarily use the data).However, as discussed above, that speed skier can also use a data unit50 with headphones 60 to acquire a real-time feedback of unwantedairtime, such as through an audible sound, so as to correct his or herform while skiing. In one aspect, the base station 70 preferably has thecapability to collect, analyze and store performance data on a server 82for later review.

Accordingly, the base station 70 includes a computer 74 to collect,analyze and process data signals to provide performance data to usersand individuals at the base station 70. The performance data isgenerally stored on a server 82, which can have an Internet connection84 so that performance data can be collected from remote locations. Ifthere are multiple users, which typically is the case, then the sensingunit 10 associated with each user “tags” the data with a codeidentifying a particular person or unit 10, such as known in the art.The server 82 then stores performance data tagged to a particularindividual or unit so that the correct information is provided, uponrequest (such as through the Internet or through the computer 74).Performance data can also be printed through printer 86 for users andpersons at the base station 70.

Although the base station 70 can be configured to process substantiallyraw data signals from units 10 (and particularly from the sensors 14),the base station typically collects performance data directly from thesensing unit 10 for each of a plurality of users and stores all thedata, tagged to the particular user, in the server 82. The stored datacan then reviewed as required. By way of example, a video station 90 canbe included with the base station 70 and users, instructors or judgescan review the performance data in conjunction with video data collectedduring the run by known video systems (or television systems).

With further reference to FIGS. 1A and 1B, the displays 24 c, 52 can beone of any assortment of displays known to those skilled in the art. Forexample, liquid crystal displays (LCDs) are preferred because of theirlow power consumption (for example, LCDs utilized in digital watches,portable computers and paging units are appropriate for use with theinvention). Other suitable displays can include an array of lightemitting diodes (LEDs) arranged to display numbers.

The headphones assembly 60 can also be replaced with a heads-up displayunit, known in the art, such as described in connection with U.S. Pat.No. 5,162,828, incorporated herein by reference.

As illustrated in FIG. 2, the invention in one embodiment operates asfollows. The sensing unit 10′ is mounted via its housing 32 to asporting vehicle, such as a snowboard or mountain bike, or such as theski 102 of FIG. 2. As illustrated, the skier 100 is catching air duringa jump off the ground 103. The skier 100 can obtain instantaneousairtime data via headphones 60′, discussed above, or he can laterretrieve the airtime data through a data unit 50′ (shown illustrativelyon the skier's jacket 100 a when typically the unit 50′ would be withina pocket or connected to a belt of the skier 100) or at a base station70′ (FIG. 1B).

FIG. 3 shows another typical use of the unit 10 of FIG. 1A. Inparticular, FIG. 3 shows the sensing unit 10 mounted onto a ski 126. Asis normal, the ski 126 is mounted to a skier 128 (for illustrativepurposes, the skier 128 is only partially illustrated), via a ski boot130 and binding 130 a, and generally descends down a ski slope 132 witha velocity 134. Accordingly, one use of a unit 10 with a speed sensor isto calculate the peak speed of the ski 126 (and hence the skier 128)over a selectable period of time, e.g., during the time of descent downthe slope 132. However, the unit 10 also provides information such asdrop distance, airtime and power, as described herein, provided theassociated sensors are included with the unit 10.

Another use of the unit 10 of FIG. 1A is to calculate the airtime of avehicle such as the ski 126 (and hence the user 128) during the descentdown the slope 132. Consider, for example, FIG. 4, which illustrates thepositions of the ski 126′ and skier 128′ during a lofting maneuver onthe slope 132′. The ski 126′ and skier 128′ speed down the slope 132′and launch into the air 136 at position “a,” and later land at position“b” in accord with the well-known Newtonian laws of physics. With anairtime sensor, described above, the unit 10 calculates and stores thetotal airtime that the ski 126′ (and hence the skier 128′) experiencesbetween the positions “a” and “b” so that the skier 128′ can access andassess the “air” time information.

FIG. 5 illustrates a sensing unit 10″ mounted onto a mountain bike 138.FIG. 5 also shows the mountain bike 138 in various positions duringmovement along a mountain bike race course 140 (for illustrativepurposes, the bike 138 is shown without a rider). At one location “c” onthe race course 140, the bike 138 hits a dirt mound 142 and catapultsinto the air 144. The bike 138 thereafter lands at location “d”. Asabove, with speed and airtime sensors, the unit 10 provides informationto a rider of the bike 138 about the speed attained during the ridearound the race course 140; as well as information about the airtimebetween location “c” and “d”.

Airtime sensors such as the sensor 14 b of FIG. 1A may be constructedwith known components. Preferably, the sensor 14 b incorporates eitheran accelerometer or a microphone. Alternatively, the sensor 14 b may beconstructed as a mechanical switch that detects the presence and absenceof weight onto the switch. Other airtime sensors 14 b will becomeapparent in the description which follows. For background, consider U.S.Pat. No. 5,636,146.

An accelerometer, well known to those skilled in the art, detectsacceleration and provides a voltage output that is proportional todetected acceleration. Accordingly, the accelerometer sensesvibration—particularly the vibration of a vehicle such as a ski ormountain bike—moving along a surface, e.g., a ski slope or mountain biketrail. This voltage output provides an acceleration spectrum over time;and information about airtime can be ascertained by performingcalculations on that spectrum. Specifically, the controller subsystem 12of FIG. 1A stores the spectrum into memory 12 b and processes thespectrum information to determine airtime.

FIG. 6 shows a graph 170 of an actual vibrational spectrum 172 acquiredby an airtime sensor 14 b (utilizing an accelerometer) during a ski jumpand stored in memory 12 b, in accord with the invention. The airtimesensing unit was mounted to a ski boot which in turn was mounted with aski binding. The sensitive axis of the accelerometer was orientedsubstantially vertical to the flat portion of the ski surface. Thevertical axis 174 of the graph 170 represents voltage; while thehorizontal axis 176 represents time. At the beginning of activity177—such as when a user of the sensing unit 10 presses the start/stopbutton 24 a—the airtime sensor 14 b began acquiring data andtransferring that data to the controller subsystem 12 via communicationlines 16 b. The initial data appears highly noisy and random,corresponding to the randomness of the surface underneath the vehicle(i.e., the ski). At time “t1” the skier launched into the air, such asillustrated as location “a” in FIG. 4; and he landed at time “t2,” suchas illustrated as location “b” in FIG. 4. The vibrational spectrum 172between t1 and t2 is comparatively smooth as compared to the spectrumoutside this region because the user's vehicle—i.e., the ski boot—was inthe air and was not therefore subjected to the random vibrations of theski slope (i.e., vibrations which travel through the binding, throughthe boot and into the sensing unit). Accordingly, the relatively smoothspectrum between t1 and t2 is readily discerned from the rest of thespectrum by the controller subsystem 12 and evaluated for airtime;specifically, airtime is t2−t1.

FIG. 6 also shows that the spectrum stops at the end 178 of the sportingactivity, when the controller subsystem stopped taking data (such as inresponse to an ON/OFF toggle on switch 24 a).

Typical accelerometer taken from a skier going down a hill is thus shownin FIG. 6. In order to determine power, or shock, in one aspect, thedata is accumulated by taking the absolute value and integrating thatdata. FIG. 6A graphically shows the result of integrating the data ofFIG. 6.

Another method of the invention for determining a measure of powerassociated with stored accelerometer data is to perform a Fast FourierTransform on the data and to integrate the magnitude to find the totalenergy associated therewith. In the plot of FIG. 6B, the data from FIG.6 was transformed with an FFT routine, and then converted to absolutevalue, point by point, and integrated, providing one measure of energy.

The data of FIG. 6 can also be reduced to a single number such as via aroot-mean-square of the data. This is done by squaring each sample ofthe data and then summing. The resultant integration can then be dividedby the duration of the data acquisition run, giving a mean, with theresulting number rooted. In the case of the FIG. 6, that would provide avalue 4.0

A microphone, also well known to those skilled in the art, detects soundwaves and provides a voltage output that is responsive to detected soundwaves. Accordingly, a microphone, like the accelerometer, mounted to thevehicle senses the vibration of a vehicle, such as a ski or mountainbike, moving along a surface, e.g., a ski slope or mountain bike trail.By way of analogy, consider putting one's ear flat onto a desk andrunning an object across the desk. As one can readily determine, themovement of the object on the desk is readily heard in the ear.Likewise, a microphone within an airtime sensor 14 b readily “hears” thevibrational movements of the vehicle on the surface. Therefore, like theaforementioned accelerometer, a vibrational spectrum such as shown inFIG. 6 is generated by a microphone-based airtime sensor during a user'ssporting activity. As above, the controller subsystem 12 utilizes thisspectrum to determine airtime.

A microphone is preferably coupled with a coupling layer of materialthat matches the impedance for the propagation of compression waves(commonly referred to as “sound waves” when in air) between theimpedance of the vehicle, e.g., the ski or board, and the microphonetransducer, thus transmitting the most “sound” power to the sensor. This“matching layer” of intermediate impedance is commonly used in sonar, asknown in the art, and it is easily applied, such as with glue.

The airtime sensor 14 b of FIG. 1A can also incorporate a switch thatrests below the boot of the ski. Through the switch, the airtime sensorsenses pressure caused by the weight of the user within the boot. Thatis, when the skier is on the ground, the boot squeezes the switch,thereby closing the switch. The closed switch is detected by thecontroller subsystem 12, FIG. 1A, as a discrete input. When a skierjumps into the air, for example, the switch opens up by virtue of thefact that relatively no weight is on the switch; and this opened switchis also detected and input into controller subsystem 12. The controllersubsystem 12 counts at known time intervals (clock rates) for theduration of the opened switch, corresponding to the jump, to determineairtime.

Another airtime sensor 14 b of the invention changes capacitance as afunction of a change of applied pressure. For example, a materialbeneath the boot that changes capacitance under varying appliedpressures can be used for this airtime sensor. The change in capacitanceis converted to a digital signal by conditioning electronics within thecontroller subsystem 12 to determine airtime.

The controller subsystem of the invention is constructed with knowncomponents, such as shown in FIG. 7, which illustrates an alternativeconfiguration to the subsystem 12 of FIG. 1A. Specifically, FIG. 7 showscontroller subsystem 150 constructed according to the invention andincluding a Central Processing Unit (CPU) 152, memory 154, interfaceelectronics 156, and conditioning electronics 158. The user interface160, such as the interface 24 of FIG. 1A, and including the buttoninputs 24 b, connects to the subsystem 150 such as shown and directly tothe conditioning electronics 158. The display 162, such as the display24 c of FIG. 1A, preferably connects to the subsystem 150 such as shownand directly to the CPU 152.

The CPU 152 includes a microprocessor 152 a, Read Only Memory (ROM) 152b (used to store instructions that the processor may fetch in executingits program), Random Access Memory (RAM) 152 c (used by the processor tostore temporary information such as return addresses for subroutines andvariables and constant values defined in a processor program), and amaster clock 152 d. The microprocessor 152 a is controlled by the masterclock 152 d that provides a master timing signal used to sequence themicroprocessor 152 a through its internal states in its execution ofeach processed instruction. The clock 152 d is the master time sourcethrough which time may be deduced in measuring velocity or air time (forexample, to determine the elapsed time from one event to another, suchas the lapsed time “t1” to “t2” of FIG. 6, the clock rate provides adirect measure of time lapse).

The microprocessor subsystem 150, and especially the CPU 152, arepreferably low power devices, such as CMOS; as is the necessary logicused to implement the processor design.

The subsystem 150 stores information about the user's activity inmemory. This memory may be external to the CPU 152, such as shown asmemory 154, but preferably resides in the RAM 152 c. The memory may benonvolatile such as battery backed RAM or Electrically ErasableProgrammable Read Only Memory (EEPROM). Sensor inputs 164 from thevarious sensors 14 are connected to the conditioning electronics 158which filters, scales, and, in some cases, senses the presence ofcertain conditions, such as zero crossings. This conditioningessentially cleans the signal up for processing by the CPU 152 and insome cases preprocesses the information. These signals are then passedto the interface electronics 156, which converts (by A/D) the analogvoltage or currents to binary ones and zeroes understood by the CPU 152.

The invention also provides for intelligence in the signal processing,such as achieved by the CPU 152 in evaluating historical data. Forexample, airtime may be determined by the noise spectra that changesabruptly, such as indicating a leap, instead of a noise spectrarepresenting a more gradual change that would occur for example when askier slows to a stop. As previously noted, a minimum quiet time isrequired, in certain embodiments of the invention, to differentiatebetween airtime and the natural motions associated with turning andskiing (e.g., jump skiing). Further, in other certain embodiments, amaximum time is also programmed to differentiate airtime from an abruptstop, such as standing in a lift line.

In accord with the invention, if speed is calculated within the sensingunit 10, FIG. 1A, then the speed sensor 14 a can incorporate one or moreof the following: (1) a pitch detection system that detects the “pitch”of the vibrational spectrum and that converts the pitch to an equivalentspeed; (2) a laser-based, RF-based, or sound-based Doppler module; (3)accelerometers or microphones; (4) pressure transducers; (5)voltage-resistance transducers; and (6) a DSP subsystem that quantifiesand bins accelerometer or sound data according to frequency. Other speedsensors 14 a will become apparent in the description which follows. Forbackground, consider U.S. Pat. No. 5,636,146.

As described above, detection of airtime is facilitated by detectingmotion, which is less difficult that determining speed. The above speedsensors are thus also suitable as “motion” detect sensors that assistthe controller subsystem 12 to logic out unwanted data, e.g., airtimedata when standing in line.

In accord with one embodiment, a vibrational spectrum is obtainedthrough an airtime sensor with an accelerometer or microphoneembodiment; and this spectrum is analyzed by the controller subsystem todetermine the pitch of the vibration and, thereby, the equivalent speed.By way of example, note that a skier generates a scraping sound onhard-packed snow and ice. When the skier changes velocity, that scrapingsound changes in pitch (or in volume). By calibrating the subsystem 12to associate one pitch (or volume) as one velocity, and so on, the speedof the vehicle (e.g., ski and mountain bike) is determined by spectralcontent. One technique for determining the “pitch” of the spectrum is todetermine the best fit sine wave to the vibrational spectrum data. Thissine wave has a frequency, or “pitch” that may be quantified and used tocorrelate velocity. The spectrum can also be sampled and “binned”according to frequency, as discussed below, to determine changes involume at select frequencies (or ranges of frequencies) which providespeed correlation.

Spectral content may be determined, at least in part, by theconditioning electronics 158 of FIG. 7. The electronics can also assessthe rise times to infer a bandwidth of the information. The conditioningelectronics 158 and/or CPU 152 can also measure the time betweensuccessive zero crossings, which also determines spectral content.

For example, FIG. 8 illustrates a spectrum 166 generated fromcombination speed and airtime sensor 14 a, 14 b in the form of anaccelerometer or microphone. The spectrum 166 thus represents anacceleration spectrum or sound spectrum such as described herein. Thecontroller subsystem 12 of FIG. 1A evaluates the spectrum 166 andgenerates a best-fit sine wave 167 to match the primary frequency of thespectrum 166 over time. FIG. 8 shows illustratively a situation where avehicle, such as a ski, moves slowly at first, corresponding to a lowersine-wave frequency, then faster, corresponding to a higher frequencysine wave, and then slower again. This pitch transition is interpretedby the controller subsystem as a change of speed. Specifically, thecontroller subsystem has calibration data to associate a certainfrequency with a certain speed, for the given vehicle; and speed is thusknown for the variety of pitches observed during an activity, such asillustrated in FIG. 8.

Variations in the character of the snow, and other environmental factorssuch as sun exposure, and user altitude, can also be factored in speedsensing, in another aspect. Further, speed spectra likely variesdepending on the characteristic spatial scale(s) of the ground, e.g.,the snow for a fixed skier speed. These spatial scales are set by thetemperature at which the snow was deposited, thawing and refreezingcycles, and the sun exposure even within a day.

It should be noted that pitch information (or volume data) is surfacedependent (and vehicle dependent). For example, aski-over-snow-speed-spectrum has a different spectrum than abicycle-over-ground-spectrum. Accordingly, different calibrations shouldbe made for different vehicles and speeds, in accord with the invention.Further, certain spectrums may actually decrease in frequency as speedincreases, which should be calibrated to obtain correct speedinformation. These calibrations are typically programmed into thecontroller subsystem memory, e.g., the memory 12 b of subsystem 12 ofFIG. 1A. Further, in certain embodiments of the invention, the sensingunit (or data unit or base station, as appropriate) stores differentspectrum calibrations for different activities so that a user can movethe sensing unit from one sport to another. Accordingly, one or morebuttons such as the buttons 24 b are used to selectively access thedifferent spectrum calibrations.

It is well known that Doppler radar is used by police vehicles to detectspeed; and a speed sensor incorporating a Doppler module can be used todetermine speed. U.S. Pat. Nos. 5,636,146, 4,722,222 and 4,757,714provide useful background.

FIG. 9 schematically illustrates process methodology, according to theinvention, which converts a plurality of acceleration inputs to speed.For example, when a plurality of six accelerometers are connected to acontroller subsystem, the process methodology of the invention ispreferably shown in FIG. 9. Specifically, six accelerometers areconnected with various sensitive orientations within a speed sensingunit 14 a to collect pitch 207 a, yaw 207 b, roll 207 c, surge 207 d,heave 207 e, and sway 207 f accelerations. These accelerations areconditioned by the conditioning electronics 158′ through the interfaceelectronics 156′ and CPU 152′ to calculate speed, such as known to thoseskilled in the art of navigational engineering (for example, GyroscopicTheory, Design, and Instrumentation by Wrigley et al., MIT Press (1969);Handbook of Measurement and Control by Herceg et al, SchaevitzEngineering, Pensauker, N.J., Library of Congress 76-24971 (1976); andInertial Navigation Systems by Broxmeyer, McGraw-Hill (1964) describesuch calculations and are hereby incorporated herein by reference). Theelements 158′, 156′ and 152′ are similar in construction to the elements158, 156 and 152 described in connection with FIG. 7.

FIG. 10 schematically illustrates further process methodologiesaccording to the invention wherein the six acceleration inputs 207 a-207f are processed by a controller subsystem of the invention (e.g.,subsystem 12 of FIG. 1A) such that centripetal, gravitational, and earthrate compensations are performed so that the various accelerations areproperly integrated and compensated to derive speed (and even directionand distance). Specifically, a controller subsystem of the FIG. 10embodiment includes a centripetal acceleration compensation section 208a which compensates for motions of centripetal accelerations via inputsof surge 207 d, heave 207 e, and sway 207 f. A gravity accelerationcompensation section 208 b in the subsystem further processes theseinputs 207 d-207 f to compensate for the acceleration of gravity, whilea earth rate compensation section 208 c thereafter compensates for theaccelerations induced by the earth's rotation (e.g., the earth rateacceleration at the equator is approximately opposite in direction tothe force of gravity).

Also shown in FIG. 10 are translational integrators 209 a-209 c whichconvert the compensated accelerations from inputs 207 d-207 f totranslational velocities by integration. Integrators 210 a-210 clikewise integrate inputs of pitch 207 a, yaw 207 b, and roll 207 c toangular velocity while integrators 211 a-211 c provide a furtherintegration to convert the angular velocities to angular position. Theangular positional information and translational velocity information iscombined and processed at the speed and direction resolution section 212to derive speed and direction. Preferably, the subsystem with thecomponents 208, 209, 210, 211 and 212 is calibrated prior to use; andsuch calibration includes a calibration to true North (for a calibrationof earth rate).

It should be noted that fewer of the inputs 207 a-207 f may be used inaccord with the invention. For example, certain of the inputs 207 a-207f can be removed with the section 208 a so that centripetal accelerationis not compensated for. This results in an error in the calculated speedand direction; but this error is probably small so the reducedfunctionality is worth the space saved by the removed elements. However,with the increased functionality of the several inputs 207 a-207 f, itis possible to calculate drop distance in addition to speed becausedistance in three axes is known. Therefore, the invention furtherprovides, in one embodiment, information for displaying drop distanceachieved during any given airtime, as described above.

As used herein, “cookie” measurements refer to one technique of theinvention for measuring speed. In this method, for example, the speedsensor drops a measurable entity—e.g., electronic charge—into the snowand then picks it up later at a known distance away to determine thespeed. The “charge” in this example is the “cookie.”

In skiing, for example, this method involves dropping a cookie as theski travels and then detecting the cookie at a known distance down thelength of the ski. The time between placement and detection given aknown length between the two occurrences determines the speed. A cookietherefore represents the placement of some measurable characteristic inthe snow underneath. This characteristic may be electrical charge,magnetic moments, a detectable material such as ink, perfume,fluorescent dye or a radiation source. The cookies may be dropped at aconstant rate, i.e. cookies per second, or at a fixed distance betweencookies. In such cases the cookies are said to be dropped in a closedloop fashion. Also the amount of charge, magnetic moment, or detectablematerial may be controlled so that the detection occurs just abovethreshold. This tends to minimize the amount of electrical power usedand to minimize the amount of material dispensed. In one aspect, thecookies correspond to dots of dye that are dropped at regularly spacedintervals and which glow when irradiated with a pumping light spectrum,for example a UV pump to drive fluorescence response in blue/blue-green,or a red pump to drive fluorescence in the IR.

In FIGS. 13 and 14, a snowboard 498 traveling in a direction 504 has twosets of electrodes attached to the ski. The first electrode set 503 isused to charge a small amount of snow 499 by applying an electricpotential across terminals 501 a and 501 b. The potential in that snow499 is then read by the second set of electrodes 502, accomplished bysampling the potential between terminals 500 a and 500 b.

Since the level of charge in the snow 499 is quite low, aninstrumentation amplifier may be used to condition the signal, such asknown to those skilled in the art. FIG. 15 shows the charge anddetection loop according to one preferred embodiment. A potential source(e.g., a battery such as battery 30, FIG. 1A) with an electrode set 503are used to charge the first electrodes 501 a, 501 b. When the output ofthe instrumentation amplifier 501 is above a predetermined threshold,the control and timing circuit 505 triggers a flip-flop (not shown) thatnotifies the controller subsystem 12, FIG. 1A, that the charge isdetected. The time that transpired between placing the charge at 503 todetecting the charge at 502 is used to determine speed. The speed is thedistance between the two sets of electrodes 503 to 502 divided by thetime between setting and receiving the charge. The functionality of thetiming and control circuit 505 can be separate or, alternatively, can beintegrated with the controller subsystem such as described herein.

The second set of electrodes 502 that is used to detect the charge mayalso be used to clear the charge such as by driving a reverse voltage(from the control and timing circuit 505 and through direct circuitry tothe electrodes 502). In this manner to total charge resulting from theski traversing the field of snow will be zero so that there will be nocharge pollution. Also it will not confuse another ski speed detectionsystem according to the invention.

In summary, the speed sensor of FIGS. 13-15 thus include two electrodepairs, 503, 502.

The situation described above is also applicable to magnetic momentcookies. In FIGS. 16 and 17, for example, a snowboard 507 showntraveling in a direction 512 has an electromagnet 511 mounted on top ofthe snowboard 507 and a magnetic sensor 510 at a rearward position. Asthe snowboarder skis along direction 512 the electromagnet 511 impressesa magnetic moment into the snow and water that resides under thesnowboard 507. This is done by asserting a strong magnetic field fromthe electromagnet 511 and through the snowboard 507 for a short periodof time. This polarization is then detected by the magnetic sensor 510.The period of time it takes from creating the magnetic moment at 511 todetecting it at 510 is used in determining the speed of the snowboard507 (such as through control and timing circuitry described inconnection with FIG. 15). The magnetic sensor 510 may also be used tocancel the magnetic moment so that the total magnetic moment will bezero after the ski travels from placement through detection and removal.

Those skilled in the art should appreciate that the elements 510, 511are shown grossly separated, for purposes of illustration. Placing theelements closer (and preferably within the same housing 32, FIG. 1A)increases the required response time of the controller subsystem, thoughit decreases the amount of power required to detect the signal (sincethe cookie signal is stronger over a shorter period).

A similar speed sensing system is shown in FIGS. 18 and 19.Specifically, the speed sensor of FIG. 18 includes an opticalcorrelation subsystem with a laser source and receiver contained inpackage 522. The laser is directed through two windows 520 and 521within a snowboard 530. The laser backscatter is cross correlated overtime between the two windows 520, 521. This means that the two timesignals are multiplied and integrated over all time with a fixed timedelay between the two signals. The time delay between the twobackscatter signals that yields the highest cross correlation is theperiod of time the snowboard takes to travel the distance of the twowindows 520, 521. The speed of the snowboard 530 is determined byknowing the window separation distance. The source does not have to be alaser but can be noncoherent visible light, infrared or any highfrequency electromagnetic radiation source.

One drop distance sensor 14 c of the invention utilizes an altimetersuch as manufactured by Sensym, Inc. The altimeter is calibratedrelative to height variations and the sensing unit 10 thereaftermonitors pressure change to assess drop distance. Accordingly, in thepreferred embodiment, such a drop distance sensor operates with anairtime sensor 14 b since drop distance is generally only meaningful inconnection with a jump. When the sensing unit 10 detects an airtime, thesame period is evaluated through the altimeter to determine dropdistance over that period. Accordingly, altimeter data should be storedin the memory 12 b (or alternatively in the memory 50 b, or in the basestation 70) for at least the period of the longest expected airtime(e.g., greater than five seconds for snowboarding, or greater than theperiod set by the user).

Drop distance can also be determined through a drop distance sensor thatincludes a plurality of accelerometers, such as shown in FIGS. 9 and 10.Through integration of appropriate acceleration vectors indicative of auser's movement perpendicular to the ground, drop distance isdetermined. A double integration of accelerometers in the directionperpendicular to ground (or thereabouts) during an airtime periodprovides the correct signals to determine skier height.

It should be apparent to those in the art that the accelerometers ofFIGS. 9 and 10 provide sufficiently detailed information such that theentire sensing unit can be mounted to a user of the system directly,rather than onto a vehicle. With the scope of the compensationsdescribed in connection with FIG. 10, for example, movements of thehuman body, e.g., centripetal motions, may be compensated for to derivespeed and/or airtime information that is uncorrupted by the user'smovements. Such compensations, however, require powerful processingcapability.

Other features can also be determined in accord with the invention suchas through measurements with the system of FIG. 10. For example, onceyou know your starting velocity, you can measure distance traveled andheight above the ground by knowing the air time for a given jump. Otherways of doing this are by using accelerometers to integrate the heightdistance. The preferred way of determining distance is to know yourvelocity at the jump start location, such as described herein, and touse the airtime to establish a distance traveled, since distance isequal to velocity times time (or airtime).

For height, a sensing unit of the invention also determines height bylooking at the time to reach the ground during an airtime. That is, oncein the air, you are accelerating towards the ground at 9.81 meters persecondˆ2 (at sea level). The sensing unit thus first determines the timefor which there is no more upwards movement (such as by using anaccelerometer or level sensor that knows gravity direction and whichchanges directions at the peak, or by using circuitry which establishesthis movement, or by determining the angle immediately prior to launchto quantify a bias distance or time to a default measure), and thencalculate the distance traveled (in height) by knowing that the defaultmeasure is equal to ½a tˆ2, where a is the acceleration of gravity (9.81m/sˆ2) and t is the airtime after the peak height is reached. If theperson does not travel upwards or downwards at the start of a jump, thenthe height is simply ½atˆ2 where t is the entire airtime.

A Doppler module can additionally provide height information; and thus aDoppler module can function as both a speed sensor 14 a and a dropdistance sensor 14 c. Further, since the impedance changes when avehicle to which the Doppler module leaves the ground, the Dopplermodule can further function as an airtime sensor 14 b. By sweeping thefrequency through various frequencies, as known in the art, the signalfrequency mix can be monitored to determine altitude relative to thedirection of the antenna lobes (typically such Doppler systems are usedas microwave ranging systems). Preferably, therefore, there are twoantennas: one to perform Doppler speed, with high spatial accuracy inthe antenna lobe so that speed is achieved, and another antenna toprovide a lobe that roughly covers the ground area in about a 60 degreecone under the user so as to achieve first-return distance measurement.With reference to FIG. 11, a Doppler module 248 functions as the dropdistance sensor and resides within a sensing unit 250 mounted to asnowboard 252 (shown in the air, above the ground 254). The radar ormicrowave beam 256 from the module 248 extends in a cone 258 toadequately cover the ground 254 so as to provide the correct measure ofheight on a first return bases (that is, any portion of the beam 256which first creates a Doppler signal sets the height; other heightmeasurements can alternatively be used, including utilizing averagereturn data). A cone 256 of angle Φ (e.g., 25-70 degrees in solid angle)provides adequate coverage. The Doppler antenna signal fills the conicalbeam 256 so as to determine drop distance from any orientation of thevehicle (i.e., the snowboard 252), so long as that orientation relativeto ground is less than the angle {tilde over (Φ)}

The Doppler module 248 may also be used as an airtime sensor since itssignal strength or form changes when the vehicle 252 is off the ground.This change of signal is thus detected by the controller subsystem todetermine airtime.

FIG. 12 shows a representative top view for one other snowboardconstructed in accord with the invention. Specifically, a snowboard 270,with boot holder 271, incorporates a sensing unit 272 constructedaccording to the invention. The unit 272 has a display 274, a userinterface 276 that provides a user with buttons to selectively accessperformance data, as described above, and one or more sensors 278 toprovide data to the controller subsystem to quantify performance data.One sensor 278, for example, can include the Doppler module 248 of FIG.11.

FIG. 20 illustrates one embodiment of a bump skier 598 utilizing twopower sensing units 600 in a mogul competition on a slope 612 (note thatthe skier is grossly over-sized relative to the slope 612, for purposesof illustration). One power sensing unit 600A mounts to the ski 602 (oralternatively to the user's lower leg 604 a), and another power sensingunit 600B mounts or attaches to the user's upper body 604. An RF signalgenerator 606 communicates (via antenna 606 a) the power values to acontroller 607 (e.g., similar to the computer and server 74, 82 of FIG.1B) at a base facility 608 (e.g., where the judges for the competitionreside). Those skilled in the art should appreciate that one or bothpower sensing units 600 can communicate the information to the base 608,as shown; however, one power unit can also communicate to the otherpower unit so that one unit 600 communicates to the base 608. However,in either case, an RF transmitter is needed at each sensing unit 600(similar to the data transmit section 22, FIG. 1A). Alternatively, otherinter-power meter communication paths are needed, e.g., wiring, laser orIR data paths, and other techniques known to those in the art, such asdiscussed herein.

The combined signals from the units 600 provides a force differentialbetween the lower legs 604 a and the upper body 604, giving an actualassessment of a competitor's performance. A computer 607 at the basestation 608 divides one signal by the other to get a ratio of the powervalues measured by the two units 600 during the run. The units 600 starttransmitting data at the starting gate 610 and continue to transmit datato the base 608 during the whole run on the slope 612. The units 600 canalso be coupled to the user via a microphone 614 (and wire 616) toprovide a hum or pitch which tells that user how effective his/herapproach is. Although it is not shown, one or both units 600 havecontroller subsystems so as to enable the features described herein inconnection with power sensing units. For example, a microprocessor canbe used to provide a power measurement in “g's” for the competitor onceshe reaches the base 608.

Those skilled in the art should appreciate that one of the units 600 canalternatively process the power values (e.g., divide the instantaneouspower value of one unit by the power value of the second unit, toprovide a ratio) generated by each of the units and can transmit a ratioof the values to the base station 608, rather than require the basestation to perform the calculation.

One accelerometer-based vibration and shock measurement system (e.g., apower sensing unit) 620 of the invention is shown in FIG. 21. System 620measures and processes accelerations associated with various impactsports and records the movement so that the user can determine how muchshock and vibration was endured for the duration of the event. Theduration is determined with a simple start stop button 622, althoughduration can alternatively start with an automatic recording that isbased on the measured acceleration floor (or by an event such astriggered by the start gate 610, FIG. 20).

In system 620, vibrations and shock associated with skiing or exerciseare measured by the use of an accelerometer 624 (or other motion orforce-measuring device, e.g., a microphone or piezoelectric device) asthe power sensor and of conditioning electronics 626 within thecontroller subsystem. The accelerometer 624 typically is AC-coupled sothat low frequency accelerations, or the acceleration due to gravity,are ignored. The accelerometer output is then conditioned by passing thesignal through a band pass filter within the electronics 626 to filterout the low frequency outputs, such as the varying alignment to thegravity vector, as well as the high frequency outputs due to electricalnoise at a frequency outside the performance of the accelerometer 624.The resulting signal is one that has no DC component and that is bipolarsuch as the waveform shown in FIG. 22.

The system 620 thus conditions the signal and remove the negativecomponents of the waveform in FIG. 22. This is done, for example, byrectifying the output of the bandpass signal. Since a positiveacceleration is likely to be accompanied by a negative of the same area,the area of the positive may be doubled to obtain the area of thepositive and negative. The signal may also be processed by an absolutevalue circuit. This can be done via an Operational Amplifier circuitsuch as the one shown in the National Semiconductor Linear ApplicationsData Book Application Note AN-31, which is herein incorporated byreference. In accord with certain processes, known to those skilled inthe art, positive values become positive; and negative values becomepositive. By way of example, the waveform of FIG. 22 is processed, forexample, to the waveform of FIG. 23.

A unipolar waveform like the one shown in FIG. 23 is then integratedover time by the system 620 so that total acceleration is accumulated.This can also be averaged to determine average shock. The signal of FIG.23 is therefore processed through an integrator (within the electronics626 or the microprocessor 628) which will result in the signal shown inFIG. 24. A power value can then be displayed to a user via the display630 (e.g., such as the display 24 c or 52, FIGS. 1A and 1B).

The period of integration may be a day or simply a single run down aslope; or it may be manually started and stopped at the beginning andend of a workout. The output is then fed into a logarithmic amplifier sothat the dynamic range is compressed. The logarithmic amplifier can beprovided within the microprocessor 628.

At any stage, the system 620 can be fed into an analog-to-digitalconverter (such as within the electronics 626) where signal processingis done digitally. The output of the accelerometer 624 should anywaypass through an anti-aliasing filter before being read by amicroprocessor 628. This filter is a low pass filter that ensures thehighest frequency component in the waveform is less than half thesampling rate as determined by the Nyquist criteria.

The accelerometer 624 output can also be processed through an RMScircuit. The Root Mean Square acceleration is then determined from thefollowing formula:$A_{RMS} \approx {\frac{1}{T}\lbrack {\int_{0}^{T}{{A^{2}(t)}{\partial t}}} \rbrack}^{\frac{1}{2}}$

where T is the period of the measurement and A(t) is the instantaneousaccelerometer output at any time t. The period T may be varied by theuser (i.e., to control the power period) and the output is a staircasewhere each staircase is of width T. This is then peak-detected and thehighest RMS acceleration is stored; and an average acceleration and ahistogram are stored showing a distribution of RMS accelerations. Thesehistograms are displayed on a Liquid Crystal graphical display 630, forexample, as a bargraph.

An alternate embodiment is to record the signal in time and transformthe signal to the frequency domain by performing a Fouriertransformation of the data (such as within the electronics 626 or themicroprocessor 628). The result is a distribution of the accelerationsas a function of frequency which is then integrated to determine thetotal signal energy contained (preferably over a frequency range). Thedistribution is, again, plotted on the LCD display 630.

Data may also be acquired by the accelerometer and telemetered to theelectronics 626 via an RF link 631 back to a remote base 632 for storageand processing (e.g., such as at the base station 70, FIG. 1B). Thisenables ski centers to rent the accelerometer system 620 which is thenplaced on a ski (or snowboard) to record a day of activity. A printoutcan also be provided to the renter at the end of the day.

A separate memory module or data storage device 634 can also be used tostore a selected amount of time data which can be uploaded at the end ofthe day. The data can be uploaded itself via a Infrared link readilyavailable off the shelf, as well as through a wire interface or throughan RF link 631.

The system 620 is particularly useful in impact sports that includemountain biking, football, hockey, jogging and any aerobic activity,including volley-ball and tennis. Low impact aerobics have become animportant tool in the quest for physical fitness while reducing damageto the joints, feet and skeletal frames of the exerciser. The system 620can be integrated within a shoe and may thus be used by a jogger toevaluate different running shoes. Alternatively, when calibrated, thesystem 620 is useful to joggers who can gate it to serve as a pedometer.The addition of a capacitor sensor in the heel helps determine averageweight. A sensor for skin resistivity may additionally be used to recordpulse. The shoe can also record the state of aerobic health for thejogger which is of significant interest to a person involved in regularexercise. The system 620 can also be used to indicate the gracefulnessof a dancer while they develop a particular dance routine. A footballcoach may place these systems 620 in the helmets of the players torecord vibration and shock and use it as an indicator of effort, or inthe “football blocking dummies” to quantify player effort.

In skiing, the system 620 has other uses since a skier glides down amountain slope and encounters various obstructions to a smooth ride.Obstructions such as moguls cause the skier to bump and to induce shock.This shock can be measured by the accelerometer 624 and accumulated in amemory 634 to keep a record of how much shock was encountered on aparticular ski run. Exercisers may use such a system 620 to grade theirability to avoid impact. A jogger may use the system 620 to evaluatetheir gate and determine their running efficiency. This becomesimportant with a greater emphasis being placed on low impact aerobics.

Those skilled in the art should appreciate that other improvements arepossible and envisioned; and fall within the scope of the invention. Forexample, the system 620 mounted on a ski may be used to determine thetotal shock and vibration encountered by a skier traveling down a slope.Mounting an additional accelerometer 624 above the skier's hip allows anisolation measurement between upper torso and ski, as described above.This can be used to determine how well a trained skier becomes innavigating moguls. This measurement of the isolation is made by takingan average of the absolute value of the accelerations from bothaccelerometers 624. The ratio of the two accelerations is used as afigure of merit or the isolation index (i.e., the ratio between twomeasurements such as on the ski and the torso, indicating how well themogul skier is skiing and isolating knee movement from torso movement).

To avoid the complications of gravity affecting the measurements ofsystem 620, a high pass filter should be placed on the accelerometeroutput or within the digital processor sampling of the output. Allanalog signals should have antialiasing filters on their outputs whosebandwidth is half the sampling frequency. Data from the accelerometers624 is preferably sampled continuously while the circuits are enabled.The processor 628 may determine that a ski run has started by a rise inthe acceleration noise floor above a preset trigger and at a setduration. In another embodiment, a table is generated within theprocessor of each sufficiently high acceleration recorded from the ski.The corresponding upper torso measurement may also be recorded alongwith the ratio of the two measurements. The user can additionallydisplay the n-bumpiest measurements taken from the skis and display theisolation index.

FIG. 25 shows a sport vehicle 700 (here shown as a snowboard) mountedwith a GPS sensor 702 (and antenna 702 a) that is coupled to acontroller subsystem 704 such as described herein. The GPS sensor 702serves the functions of one or more of the sensors 14, FIG. 1A. As knownin the art, GPS receivers such as the sensor 702 provide absoluteposition in terms of altitude and earth location. By monitoring thesignal from the GPS sensor 702, speed, height and loft time are directlydetermined. For example, at each signal measurement, a difference iscalculated to determine movement of the vehicle 700; and that differenceis integrated to determine absolute height off of the ground, distancetraveled, speed (i.e., the distance traveled per sample period), andairtime. FIG. 25 thus illustrates a sensing unit which includes a GPSsensor 702 (operating as one or more of airtime, speed and drop distancesensors) and a controller subsystem 704, such as the subsystem 12 ofFIG. 1A.

FIG. 47 illustrates one GPS-based system of the invention, including aGPS receiver 1400 with an antenna 1401. The antenna is small because GPSoperates at an extremely high frequency. The antenna 1401 may be mountedwith a backback, of the user, containing the GPS receiver. The receiveris powered by a battery back 1402 which also powers a microprocessor1403. The microprocessor 1403 takes data from the GPS receiver 1400 andstores it as a position in random access memory RAM 1404. The data ispreprocessed according to a program stored in Read Only Memory ROM 1405.The processor ROM 1405 can also contain stored maps with which todetermine skier performance, allowing the program to become an expertsystem to, for example, identify trail features or problems. The userinterfaces with the microprocessor 1403 via the peripheral interface1406. Examples of a peripheral interface include keyboards, displays,etc. A panic button can be included with the interface 1406 to inform abase station of trouble. The warning is sent with exact location so thatthe rescue team (e.g., the ski patrol) can easily find the strickenperson (e.g., skier).

An enhancement to the above system utilizes differential GPS.Differential GPS makes use of the property that a fixed receiver in aknown position can be used in conjunction with a non-stationary GPSreceiver with the effect that many of the large errors are rejected. Theresult is a more accurate position solution for the moving receiver. Inthe preferred embodiment, a user carries the receiver 1400 and the basestation houses the differential model, as known in the art.

For skiing and other similar sports, the user is given a GPS receiverand an RF link (e.g., a transmit section 22, FIG. 1A) so that a centralcomputer at the base station lodge (e.g., station 70, FIG. 1B) knows thelocation of every user. Such locations may then be broadcast to theskier for display in a set of goggles using a heads-up display.

FIG. 26 shows a strain gauge 720 connected to a controller subsystem722, such as the subsystem 12 of FIG. 1A. In the illustrated embodiment,the sport vehicle is a ski or snowboard 724. Those skilled in the artunderstand that strain gauges can detect stress associated with thesurface that the gauge is mounted upon. The gauge 720 thus senses whenthere is little or no stress on the snowboard 724, such as when thesnowboard 724 is in the “air”; and the subsystem 722 then determinesairtime from that relatively quiescent period. FIG. 26 thus illustratesa sensing unit which includes a strain gauge 720 as an airtime sensorand a controller subsystem 722. The sensing unit 720/722 can furtherprovide factors such as power, by utilizing the signal generated by thestrain gauge 720 as a measure of the punishment that the user applies tothe vehicle 724. Accordingly, the gauge 720 can operate as a powersensor in addition to an airtime sensor.

In an alternative embodiment, the element 720 is a temperature gaugethat senses the change in temperature when the ski 724 leaves theground. This change of temperature is monitored for duration until itagain returns to “in contact” temperature. This duration is then equatedto “airtime” or some calibrated equivalent (due to thermal impedance).Note that the impedance of air is different from snow; and hence thatchange can also be measured to determine airtime.

In an alternative embodiment, the element 720 is a load cell, known inthe art, such as a strain gauge bridge, or other force-sensing means,such as force sensing resistors (FSRs). A unit incorporating suchelements operates as described above.

FIG. 27 shows one speed, airtime and power sensing unit 740, constructedaccording to the teachings herein, and mounted to a sporting vehiclesuch as the ski 741. The unit 740 has an RF transmitter 742 (e.g.,similar to section 22, FIG. 1A) to communicate signals from the unit 740to a watch 744 worn by the user (not shown). In this manner, the usercan look at the watch 744 (nearly during some sporting activities) tomonitor performance data in near-real time. A small watch display 744 aand internal memory 744 b provide both display and storage for futurereview.

The devices for measuring speed, airtime, drop distance and power asdescribed herein can oftentimes be placed within another component suchas a user's watch or a ski pole. For example, the power system 620 ofFIG. 21 is readily placed within a watch such as watch 744, and withoutthe unit 740, since power integration can be done from almost anywhereconnected to the moving user. Likewise, airtime measurement through theabsence of a spectrum, such as shown in FIG. 6, can also be done in awatch or a ski pole. Speed measurements, however, are much moredifficult if not impossible to do at these locations because of the lackof certainty of the direction of movement. However, with the increasedperformance and size reductions of guidance systems with accelerometers(see FIGS. 9 and 10), even this can be done.

FIG. 28 illustrates one drop distance sensing unit 800 for determiningdrop distance from a skier or snowboarder 801 (or other sportenthusiast, e.g., a mountain biker, skateboarder, roller-blader, etc.).The unit 800 includes an antenna 802 and a GPS receiver 804. The GPSreceiver operates such as known in the art. Although the unit 800 isshown on the skier's waist 806, the unit 800 can also be coupled to thesnowboard 808 or it can be constructed integrally with the user's watch810. In the embodiment shown, the unit 800 can include a second antenna812 (or other data transfer mechanism, including IR techniques) whichcommunicates with the watch 810 so as to send performance data thereto.

FIG. 29 illustrates a block diagram of the drop distance sensing unit800, including further detail therein. A microprocessor 809 connectswith the GPS receiver 804 to process GPS data. In particular, the GPSdata is known to include three dimensional data including height off theearth's surface. The processor 809 thus processes the data atpredetermined intervals, e.g., about 1 second or less, to determine thechange of height from the last measurement. Accordingly, when airtime isdetermined, according to the teachings herein, the device 800 alsodetermines drop distance for that interval. The drop distanceinformation is stored in internal memory 812 so that it can be retrievedby the user or transmitted to a data unit such as the watch 810. Recordsof drop distance can also be stored within the memory 812 such that apeak drop distance and a series of drop distances can be stored andretrieved by the user at a later time. The device 800 also includes abattery 814 and other interconnections and processing electronics (notshown) to operate the device 800 and to provide drop distance data, asdescribed in connection with FIGS. 1A and 1B. A data transmit section816 (e.g., the section 22, FIG. 1A) transmits data via an antenna 816 a(or other technique), as desired, to the watch 810 or to other displaysor data units, or to the base station, such as discussed herein.

Evaluation System

The sensing units described herein can be complex, and require lengthyevaluation to provide a robust system. To evaluate such units, a dataevaluation system was developed, as described next. The data evaluationsystem provides a flexible data recording unit that has applicability inseveral circumstances where large amounts of data are collected inadverse and remote environments.

As shown in FIG. 30, the Data Acquisition system 899 includes five maincomponents on a data acquisition/playback board:

Data Recorder/Player 900

PC Interface 902

Analogue Motherboard 904

Analogue Input Interface Boards 906

Analogue Output Interface Boards 908

To record information, the Data Recorder/Player board and AnalogueMother Board 900, populated with the required Analogue Input InterfaceBoards, are placed in a box, connected by a small back plane. Once thedata has been recorded, the Data Recorder/Playback Board 900 is removedfrom the box, and connected to the PC Interface board. The PC thencontrols the downloading of data to file.

The overall size of the Recording Package is 2½″ wide, 5½″ deep, and 4½″tall. All sensors are external, and may or may not be housed in boxes.

The data recorder and player 900, FIG. 31, is the heart of the system899. It includes a block of memory 910 for holding the sampled datavalues, controlling logic 912, and interfaces 914 a, 914 b.

The Data Recorder/Player Board (DRPB) 900 always handles 32 bits ofdata. It is configured to either Record or Playback the data at a rateof one word (32 bits) every 15.6□S (approx. 64 KHz). The controlinterface 914 provides signal to interface to the PC Interface board andAnalogue Mother Board.

The Control Logic 912 also provides refresh cycles for the dynamic RAMs.The Memory 910 consists of any 72-pin SIMM modules. These must bematched in the same manner as when used in a PC. (i.e. one 8 Mb cannotbe mixed with one 16 Mb module.) This provides a limit of 512 Mb of RAM,which will give a maximum of 134217728 samples. This is equivalent to 34minutes and 53 seconds. However, the larger SIMM's are physically tallerthan standard-sized devices and are very expensive. In practical terms,two 64 Mb SIMMs (128 Mb) provide 8 minutes and 43 seconds of datarecording at 64 KHz.

The recorder can be paused during testing. Longer recording periods makeannotation of the data (and data handling) more difficult. If this limitis acceptable, two of the SIMMs can be removed from their sockets in theDRPB 900, to reduce its size.

The DRPB 900 has its own NiCAD battery (attached to the board forsafety) such that the board can be removed from the box on the ski andtaken to the PC for downloading.

PC Interface

The PC Interface 902 allows the DRPB 900 to be connected to the parallelport of a PC. It requires a bi-directional port (EPP). The design usestwo MACH 210 s, and allows the PC to control the upload and downloadprocess completely. The current download/upload rate achieved is 8Mbytes/minute which is generally acceptable.

Analogue Mother Board

The Analogue Mother Board (AMB) 904 controls the sampling of the data onthe Analogue Input Interface boards (AIIBs) 906. It presents the DataRecorder/Player 900 with 32 bits of data for each recording period. Datafrom the AIIBs 906 are multiplexed. The programming of the AMB 904determines the sampling rates and position of the data in the 32-bitword for the AIIBs 906. If a different combination of AIIBs is required,the AMB 904 is reprogrammed. Therefore, the control logic on the AMB 904is held in an AMD MACH 211 which is a flash device, programmable whilststill on the board using a JTAG connector (thus a notebook PC with aparallel port can reconfigure the board.)

As shown in FIG. 32, the Control Logic 912 inserts the real time clock916 value into one channel (probably an 8 KHz channel). This will simplybe a counter counting at a minimum frequency of 8 KHz, which allows theanalyzing software to detect when the recording was paused.

Analogue Input Interface Boards

The Analogue Input Interface boards 906 are small daughter boards whichplug in vertically to the Analogue Mother Board 904 (i.e., into theslots 918, FIG. 32). The Mother board 904 will allow 8 of these boardsto be connected at once. This design allows an interface board to suitthe signal to be recorded. This is then combined with other interfaceboards to allow recording of a combination of signals, as required.

As shown in FIG. 33, the A/D converter 920 is a serial device; thusreducing the number of pins required and the level of board complexity.The board space available for Analogue Signal Conditioning 922 islimited. The Pressure Sensor AIIB 906 (i.e., that board incorporating adrop distance sensor, discussed above), shown schematically in FIGS. 34Aand 34B, provides an example of the size limitations, and the complexitylevel limitations on the circuitry. Specifically, the circuit 930 ofFIGS. 34A and 34B is an example of an AIIB 906 for a SenSym Pressuresensor. It uses four op-amps and various capacitors and resistors toprovide the required signal conditioning.

FIG. 35 exemplifies a layout board 940 for circuit 930, FIGS. 34A and34B, used to connect to the AMB 904. The height of the board 940 is0.9″, and the width is approximately 2½ inches.

Preferably, one AIIB 906 incorporates a Voice Annotation Channel, sothat data can be annotated by voice concurrently with data acquisition.The AIIB 906 for the Voice annotation channel can have a simple tonegenerator connected to an external button that is operated by the skier.This will inject a tone when pressed onto the voice channel to allowmarking in the annotation of special places.

The analog interface boards 908 are similar to the AIIBs, but have a DACrather than ADC components. They allow the system to generate signals asrecorded from the sensors. Thus a new board design can be tested on avirtual slope on the bench.

The data acquisition system thus permits the capture of data, real time,to evaluate sensors such as altimeters used in a drop distance sensor,described herein. Two exemplary altimeters, for example, are the SenSymSCX15AN Pressure sensor and the SenSym SCX30AN Pressure sensor.

As discussed herein, many embodiments of the invention utilize piezofoils, such as within airtime, power, and speed sensors. These foils forexample include those foils from AMP Sensors, such as the AMP DT0-028Kfoil or the AMP LDT1-028K foil. Similarly, an accelerometer like the AMPACH-01-03 accelerometer can be used to generate vibration data (thissensor was in fact used to collect the data of FIG. 6).

Another pressure-based drop distance sensing unit 1000 of the inventionis shown in the block diagram of FIG. 36. The unit 1000 includes apressure sensor 1002, as described above, and is used to determinealtitude. GPS, as described above, may also be used in connection withthe unit 1000. The pressure sensor altimeter 1002 is used to determineambient pressure. As altitude changes, so does the pressure. Thepressure sensor 1002 indicates pressure by an analog voltage. Thatvoltage is conditioned by the conditioning electronics 1004 so that theoutput data is filtered, well-behaved and has an appropriate scalefactor. The electronics 1004 also typically filter the signal to preventaliasing when sampled by the controller subsystem 1006. Afterconditioning, the data is converted to a digital word by A/D electronics1008 for the microprocessor 1006. The data is thus represented as aneight, twelve or sixteen bit word. It is then read by the microprocessor1006 and is interpreted as altitude.

As illustrated in FIG. 37, the processor 1006 includes resident softwarethat schedules the reading of data and its manipulation thereof. Thecore shell of software is the Real Time Operating System 1010. This maybe purchased off the shelf by companies such as Ready Systems. Theseprograms process tasks according to user selected priorities so thatevery task is executed within a software control frame. The part of thesoftware that reads the pressure sensor output (from the A/D 1008′) iscalled the Input Output Driver or I/O Driver 1012. This program may beexecuted on a regular basis automatically or may be the result of aninterrupt. In the event of an Interrupt, the processor 1006automatically launches an interrupt service routine or ISR. The purposeof an ISR and I/O Driver 1012 is to get the data into the processor'smemory so that an application program may use the information. Filteredby the I/O Data 1013, the application 1014 is the software thatinterprets the data, such as to determine altitude 1016. The data maythen be stored in memory for other applications 1014 to operate on thedata, use it for decision making, or pass it on to other I/O Drivers foroutput.

The processing of altimeter data from the pressure sensor 1002 is amatter of eliminating the low and high frequency noise from themeasurement. In this embodiment, this is done by cascading a high passwith a low pass filter. The Low pass filter is selected by determiningthe sampling rate and ensuring that the highest frequency component inthe signal passed through the filter is half the sampling rate, known asthe Nyquist criteria. Frequencies that are higher than half the samplingrate will result in aliasing. This means that the spectrum will bedistorted and the original signal is not accurately reconstructed.

The high frequency component of the cascaded high pass, low pass filteris thus selected by the maximum rate of descent the skier will travel.The higher the low pass filter, the faster the altimeter tracks theskier. Since the skier is limited by inertia and kinematics (the basiclaws of motion) the rate of altimeter change is not high by signalprocessing standards. If a skier travels at 100 ft per second, this isabout 68 miles per hour, which means that if they move along truevertical their altitude would be changing at 100 ft/sec. If the changein output voltage goes from DC to 100 Hz, then the low pass filter alsoneeds to pass the 100 Hz.

The low frequency of the high pass, low pass filter is related to howslow the signal changes. In this case it is limited by the frequencyresponse of the altimeter and the slow changes associated withatmospheric fluxuations.

FIG. 38 shows a “shock” or “G” or power digital watch 1020 constructedaccording to the invention. As in normal watches, a band 1022 securesthe watch 1020 on a user's wrist so that the watch face 1024 can beviewed. A crystal 1026 provides the primary window through which to viewdata such as time on the display 1028. A user can adjust the timethrough a knob such as knob 1030.

The watch 1020 also holds a power sensing unit 1032, as describedherein. The unit 1032 utilizes either its own microprocessor (e.g., acontroller subsystem), or augments the existing microprocessor withinthe watch 1020 to provide like capability. The unit 1032 is controlledby interface buttons 1034 a, 1034 b, such as to provide ON/OFFcapability and to display power performance data instead of time on thedisplay 1028.

The watch 1020 of FIG. 38 thus provides “power” without the additionalmounting of a sensing unit on a vehicle. Rather, this embodiment takesadvantage of the fact that many sports include waving and movement ofthe user's arm (e.g., tennis and volleyball); and thus power isdetermined through the techniques herein to inform the user of thisperformance data, through the watch 1020.

FIG. 39 illustrates another watch system 1040 for measuring power andinforming a user of that power. As above, the watch 1042 is made tomount over the user's wrist. The watch 1040 functions as a normal watch,including, for example, a display 1044 to tell the user time (e.g.,“10:42 PM”). Another portion of the watch includes a power sensing unit1045, a processor 1048, force sensing element 1050 (e.g., a power sensorsuch as an accelerometer, or alternatively a microphone) and circuitry(not shown) to drive a display that informs the user of power. Theprocessor 1048 processes the force data from the sensor 1050 and sends asignal to the display 1052 so that the user can see the powerperformance data (e.g., “50 G's”). The units on the display 1052 neednot be actual units, such as G's, but relative units are acceptable tocalibrate to other users and to repeated activity by the same user. Acontrol knob 1054 provides access to the unit 1045 in a manner similarto the user interface buttons of FIGS. 1A and 1B.

Those skilled in the art should appreciate that an altimeter can also beplaced in the watch 1040 so that, as above, the user is informed of dropdistance. The button 1054 can also enable control of the unit 1045 sothat one of drop distance, or power, is displayed on the display 1052.This dual drop distance and power watch embodiment is described in moredetail in FIG. 40.

FIG. 40 illustrates one block diagram of a power/pressure watch system1060, constructed according to the invention. An altitude or pressuresensor 1062 as discussed above is conditioned by conditioningelectronics 1064 which filter and scale the sensor's output. The data isthen converted to digital by the Analog to Digital electronics 1076. Thedata is then read by the microprocessor 1066, wherein the data isprocessed by software and interpreted as altitude. The watch system 1060includes a keyboard interface 1068 to set the time and the differentperformance data modes, as commanded by the user. Time is displayed onthe watch display 1070, as normal.

System 1060 can further include an accelerometer 1072 which sensesvibration and shock, as described herein, and which provides a voltagethat is proportional to acceleration. This output is then conditioned bythe conditioning electronics 1074 for scaling and filtering (such asthrough a combination of low pass and high pass filtering): the highfrequencies limit is selected by anti-aliasing requirements while thelow frequency limit is determined by low frequency noise rejection. Thedata is then sampled by the analog to digital electronics 1078 and readinto the microprocessor 1066.

Drop distances may thus be determined by various sensors, includingaccelerometers, differential Global Positioning System (GPS) receivers,and pressure sensors, as discussed above. These sensors may be used inconjunction with airtime logic—which for example senses the abruptchange in the vibratory noise floor, potentially indicating the skierleaving contact with the ground—to give useful drop distancescorresponding to airtime.

Accelerometers can also be used to determine airtime and the onset offree-fall. By using accelerometers to look at the ski vibration, airtimecan be determined by absence of the vibrating spectrum, suggesting thatthe skis are no longer rubbing along the ground. Generally, thiscorresponds to the high frequency component to the acceleration signal.Accelerometers in the prior art also measure the acceleration due togravity, which tends to change slowly. When a body free-falls, the forceon the seismic mass associated with the accelerometer is zero becausethe seismic mass is no longer restrained. An accelerometer suite thatmeasures acceleration in three translational directions will sum to zeroin a free-fall. When the gravity acceleration returns, noted by thereturn of the low frequency acceleration floor, as well as by the returnof the high frequency noise floor from skis rubbing on the ground, thesystem can determine the duration of free-fall—i.e., drop distance. Theminimum distance d traveled in this free-fall along the axis of gravityknown as true vertical may be determined by the formula d=vot+½gt2,where d is distance traveled downward, g is acceleration due to gravity32 ft/sec2., vo is the initial velocity downward, and t is the number ofseconds of free-fall. If the initial velocity vo is not known then theminimum distance dmin can be determined by the rest of the equationdmin=½gt2.

FIG. 9 showed the hardware block diagram for an accelerometer suite 207capable of determining loft and free fall. The diagram included threelinear accelerometers whose output are conditioned by electronics thatstrengthen and filter the signals. The output of the conditioningelectronics is then fed into interface electronics that convert thesignals from analog to digital.

FIG. 41 illustrates a top view of one preferred system 1100 fordetermining power and/or airtime (and/or speed discussed in more detailbelow). The system 1100 includes a sensing unit 1100 a with housing 1102mounted to a snowboard 1104 (alternatively, the system 1100 can bemounted to a ski, windsurfing board, bike, etc.) and a data unit 1100 b,such as a data collection watch 1112 (such as the datawatch by Timex®).The housing 1102 forms an enclosure for the sensor, here illustrated asa piezo strip 1108 such as made by AMP Sensors, in Pennsylvania. Thestrip 1108 connects with the housing 1102 to measure sound within thebox 1102. The box 1102 thus serves to amplify the sound heard throughthe ski 1104, and also compresses air within the box 1102 in a mannerthat is indicative of the force experienced by the box and thus the ski1104. Accordingly, the strip 1108 measures not only sound, but aforce-related factor that is used to determine power. In this manner, amicrophone (e.g, the strip 1108) is suitable to measure both airtime andpower. Further, by monitoring the pitch or signal strength of the soundwithin the box, a speed can be correlated with the sound. Accordingly,by a single microphone such as a piezo strip 1108, airtime, power andspeed (or at least motion) are provided. A controller subsystem 1110connects to the strip 1108 to process transducer data; and thatprocessed data is transferred, for example, to the watch 1112 worn bythe user by way of infrared energy signals from a diode/detector pair1114 a/b or other similar optical data transfer devices. The units 1100a and 1100 b preferably permit communication between units, eitherdirection.

Other transducers, e.g., an accelerometer or altimeter 1116 can also beplaced in the box 1102 for processing and transfer to the user's watch1112. The box 1102 is preferably sealed against environmental effects soas to protect the electronics therein. It is thus similar to the housing32 of FIG. 1A. Because of the watch 1112, there is no separate need fora display in the sensing unit 1100 a. A battery (not shown) powers theunit 1100 a.

Another microphone such as the strip 1108 a can also be included withinthe unit 1100 a to provide additional speed sensing capability, asdescribed below.

FIG. 42 illustrates that at the onset of airtime, the controllersubsystem can trigger a drop distance calculation. Specifically, at anairtime sensed by an airtime sensing unit, a drop distance sensor—e.g.,a GPS receiver, altimeter, or accelerometer—is polled to determine thechange in vertical direction. In the event of a vertical drop, the firstderivative in the z direction (True Vertical) should be a maximum. Thesignal flow diagram of FIG. 42 illustrates this logic:

Specifically, loft condition is first determined by the airtime sensorof block 1200. This data state is determined, for example, by the suddenabsence of noise in the ski, causing an abrupt change in the near noisefloor. The next data state is characterized by blocks 1202, 1204 and1203. In state 1202 an altimeter is polled to determine if altitude ischanging at a high rate, such as a rate associated with free fall. Ifso, the drop distance data is accumulated for the duration of the highfree fall rate and the airtime. The state 1204 is similar to that of1202, except for GPS receiver signals. In state 1204, GPS data isevaluated for a high rate of change in the Z direction. If there is ahigh free fall rate, the data is accumulated for as long as both thehigh rate and loft time are valid. The state 1203 corresponds to a datastate using accelerometer data evaluation for airtime. As before, if theuser is in free fall, the accelerometer does not experience anacceleration due to gravity. During this condition, drop distance datais accumulated during the airtime to determine vertical drop. The end ofairtime signifies the end of the vertical drop, and state 1206 isreturned. The distance of the drop is provided by the accumulation ofthe altimeter change, the change in GPS vertical height, or the durationof the accelerometer free fall and the laws of physics, as describedherein.

FIGS. 43 and 44 provide vibrational data corresponding to accelerometerdata at less than 2 mph, FIG. 43, and greater than 15-20 mph, FIG. 44.The data acquisition system was the same as for the data of FIG. 6. As aski moves faster over the surface of the snow, more of the energy fromthe spectrum is associated with the higher frequency components.Specifically, it is readily seen that the FIG. 44 has more power athigher frequency components. By segmenting and “binning” thesefrequencies, energy is isolated to such frequencies so that it can becompared to calibrated speed data at those frequencies. This isdescribed below.

Note first that a microphone can provide basically the same informationas the accelerometer above (that is, the data of FIGS. 43 and 44 appearsimilar to microphone data taken within a unit such as described inconnection with FIG. 41), at least in frequency and relative magnitudes.Microphones are cheaper than accelerometers, and thus they are preferredfor production reasons.

With regard to FIG. 45, a force measuring sensor such as a microphone oraccelerometer generates a voltage signal indicative of the spectra suchas within FIGS. 43 and 44. This voltage 1300 is passed through an arrayof temporal filters which “bin” the appropriate results, according tofrequency, such as shown in block 1302. The temporal binning of block1302 can include a series of analog networks that pass specificfrequencies only. For each frequency bin, the data is processed bymodules 1304: the data is first rectified at block 1306 and a capacitor1308 charges over the time constant of an A/D 1310 to integrate thesignal of those frequencies; whereinafter the switch 1312 discharges intime for the next sample. The output is then summed according tofrequency, for subsequent summing.

Those skilled in the art should appreciate that the process of FIG. 45can be done within a DSP, wherein the steps of blocks 1302 and 1304 areaccomplished through software modules. Accordingly, the unit 10 of FIG.1A can thus simply process the data 1300 within the microprocessor 12 a,or the logic functionality can be maintained in analog such as withinthe logic 12 c or within other electronics not shown.

In any event, the various frequencies are then binned. For example, thelow frequency 0-1 Hz is binned into the first bin, the 1-10 Hzfrequencies are in the next, and so on (similar to the equalizer lighton the home stereo system). For each time T (set by the A/D or othertime—which is preferably at a reasonably fast rate, e.g., 100 Hz), thepower in each frequency is integrated and assigned an integer value,such as: a typical value within 0-1 Hz is 1, a typical value within 1-10Hz is 1, and so on. These values are integrated at a user selectedinterval (i.e., the power period). Further, the power values arepreferably standardized to every user, so if you have 5 seconds of peakpower activity, that will be saved—this number should be changeable to10 seconds or even 1-5 minutes. A table created by this technique mightappear as in Table I: TABLE 1 Typical Frequency Binning, for Speed,Airtime and/or Power Frequency 0-1 Hz 1-10 Hz 10-100 Hz 100-100 Hz A/DSample 1 1 .5 1 .1 A/D Sample 2 2 1 2 .3 A/D Sample 3 1 2 1 .4 A/DSample 4 2 1 3 .3 . . . . . . . . . . . . . . . A/D Sample n X1 X2 X3 X4SUM over time 1-n 6+ . . . +X1 4.5+ . . . +X2 7+ . . . +X3 1.1+ . . .+X4

With time 1-n corresponding to the power period, power values arefunctionally dependent upon the SUM values, either within some or all ofthe bins. Note that the bins of FIG. 45 and Table 1 are chosen forillustrative purposes only; and that other bin sizes and ranges can beused in accord with the invention.

Fortunately speed can also be determined through these SUMs (althoughthe summing “period” should be much faster than for power, and shouldtypically be less than one second or even one tenth of a second). Asnoted above, there is a lot more high frequency content at fasterspeeds, FIG. 44, as compared to lower frequency content, FIG. 43. So,speed can also be correlated to such binned data, after obtaining asufficient database of samples (preferably corresponding to theparticular vehicle). Further, not all binning sections need to be usedin that correlation. For example, one of the binning sections mightreadily produce a four factor increase of power for 15 mph as comparedto 3 mph; and such increase is repeatable to correlated data.

Again, data for speed should not be integrated over time 1-n; but rathershould be assessed for each sample or groupings of sample (e.g., anaverage of samples over a 1/10ths period). If for example a group ofsamples over any one second specify 15 mph data, then the speed sensingunit should report “15 mph event recorded”. If only one sample has thisvalue, then it should be discarded since—relative to 1/10s intervals—thespeed is substantially “steady state”. That is, an average of ten speedsummations over one second should, on average, all report the same 15mph event.

The data of Table 1 can be also used for power. In one preferred aspect,power is a factor which is scaled to the third derivative of verticaldistance moved with respect to time, essentially the change ofacceleration (in the perpendicular axis to the ski or snowboard, ifdesired, or some other orientation) as a function of time. Specifically,power can be measured as:${Power}\therefore{\frac{\partial^{3}x}{\partial t} \approx \frac{\partial A}{\partial t}}$

where x is distance moved in the selected direction (here, vertical tothe ski face), and A is acceleration in the same axis.

In summary, selectable integral periods for power (e.g., 5 seconds, or 5minutes, or other user-selected power period), and for speed (e.g., lessthan one second) are preferable, in accord with the invention. Note alsothat the filter bank 1302 is preferably adjustable and not limited to0-1 Hz, 1-10 Hz, 10-50 Hz, and 50-250 Hz.

FIG. 46 illustrates the capture of data 1300′, such as digital or analogdata from an accelerometer, by a DSP 1304′ within a sensing unit of theinvention. The DSP converts data 1300′ to power by one of severaldisclosed algorithms: by evaluating one or more frequency ranges of thedata 1300′, by determining vertical motion relative to a face of thevehicle and assessing that motion with an exponential factor for aselected time period, or by determining a vertical velocity relative toa face of the vehicle and assessing that velocity with an exponentialfactor.

Note also that airtime can also be isolated from the data of Table 1.For airtime, the low frequency bins of 0-1 Hz and especially 1-10 Hzwill be very small; and the controller subsystem will immediatelyidentify this loss of power, in these binned frequencies. Since airtimecan be less than one second, the moving averages which integrate thedata should be substantially less than the airtime minimum. Essentially,the airtime binning is a one-dimensional convolution between a rectfunction (defining the period) and the data of the lower frequency bins.A similar convolution can be applied to determine factors such as powerand speed, except that the rect size is larger and different bins arelikely used.

Power can be determined in other ways too, in accord with the invention.Specifically, power can be defined as the rate at which energy E isexpended. Power and work are related by:P=dE/dt

By having an estimate of the energy associated with the user's movement,over time, then an estimate is also available for the power expended bythe user. The kinetic energy of a simple mass is expressed by:E=½mV2

Thus energy is proportional to velocity squared. Velocity, or speed, isdetermined in several ways herein. For example, velocity can bedetermined from an accelerometer by integrating acceleration over timeafter subtracting the 1 g acceleration of gravity. In a sampled system,velocity at any point in time (at interval Δt) is equal to:V≈ΣAΔt

where A is the measured acceleration with the 1 g acceleration removed.Velocity is squared to obtain a quantity proportional to the kineticenergy:E=V2The total power over some finite time interval N is thus proportionalto:$P \approx {\frac{1}{( {N - 1} )\Delta\quad t}{\sum\limits_{i = 1}^{N}( {V_{i}^{2} - V_{i - 1}^{2}} )}}$

If for example the accelerometer is attached to a ski or snowboard, thena significant portion of the measured acceleration may be due to theoscillations of the ski/board at its resonant frequencies. Theseoscillation are the ski/board's response to its dynamic loadingenvironment and may not be indicative of the power that theskier/boarder experiences. It is therefore worthwhile to process theaccelerometer signal so as to reduce the contribution made by ski/boardvibration to the power measurement. The resonant frequencies of theboard and skis are significantly higher than the dynamics that theskier's body experiences. Thus, the contribution of the ski/boardresonant response to the accelerometer measurement can be reduced byapplying a low pass temporal filter to the data prior to integration.

One way of developing an algorithm to deal with extracting speed fromacceleration data (or microphone data or other force sensing output) isthrough a neural network. A neural algorithm is one that is developedthrough a learning process, including force sensing data from the sensorand speed data correlated during test. The neural algorithm builds anetwork that will process the data. It starts off by using a smallnumber of samples and a small number of stages. The output is derived byweighting factors on the samples and added together. The output becomesa weighted average of the inputs, i.e., a multiple stage moving averagefilter. The output is then compared with the speed waveform and testedto see how well it produces the correct result. If the test fails, thenumber of samples is then increased or the number of stages isincreased, or both. FIG. 48 illustrates an exemplary neural network 1498windowing down acceleration data 1500 to achieve the correlated speed1502. Specifically, FIG. 48 shows the construction of a network 1498where four samples 1,2,3,4 are fed into four stages 1504, and where eachsample is multiplied by a weighting factor or gain. The network 1498 isthen tested to see if input data produces speed data. If not the numberof samples used as input are increased as are the number of stages. Ateach network the relative gains are also changed to see if that willproduce the required result.

Other Techniques for Speed Estimation

In accord with the invention, speed can also be determined based uponthe characteristics of the resulting friction-induced noise spectra.When the vehicle—be it a ski, snowboard, waterski, etc.—passes over thesurface, the spectra will have a bandwidth content that increases withvehicle speed in a deterministic fashion (if one can assumes that thespatial spectral content of the surface is invariant with respect totime and location). As such, the following describes a two-sensortechnique for estimating delay times of transport processes. The unit1102 of FIG. 41 includes two such sensors—i.e., the two piezo strips1108—which are suitable for such process measurements.

Consider the system 1600 depicted in FIG. 49. A ski or snowboard 1602 isinstrumented with two vibration sensors 1604 such as described above.These sensors 1604 are attached a distance “D” apart. The ski moves at avelocity “V” over the snow surface 1606. The front-most sensor 1604 aprovides a vibrational output s2(t), a typical example of which isplotted in FIG. 50. The rear-most sensor 1604 b provides a vibrationaloutput s1(t), plotted in FIG. 51. Assuming that the characteristics ofthe snow surface 1606 which induce the response s2(t) do not changesignificantly as the ski 1602 passes through a distance D, and that thespeed of the ski 1602 does not vary significantly over that time, thens1(t) will essentially be a replica of s2(t), delayed by an amount oftime □. This is seen by considering the feature of the vibration spectraat time t0 in FIG. 50. This trace can be conceived of as “sliding” alongthe time axis t to produce FIG. 51, except now the aforementionedfeature of the time trace appears at time t0+□.

If one estimates the time delay t accurately, then one simply uses therelationship DISTANCE=VELOCITY □ TIME to infer the velocity V:$\begin{matrix}{V = {\frac{D}{\tau}.}} & (1)\end{matrix}$

This same methodology has been applied in measuring the characteristicpropagation times (and thence speeds) of spatial features in turbulentflow over wings and other surfaces.

Since the vibrational input can be thought of in a local frame (the“sensor frame”) as a random process, one can use conventionalstatistical means to infer the delay time t, and thence V. Typically,this is done using correlation functions. Define the cross correlationfunction R12(□) as $\begin{matrix}{{R_{12}(\tau)} = {\lim\limits_{Tarrow\infty}{\frac{1}{T}{\int_{0}^{T}{{s_{1}(t)}{s_{2}( {t + \tau} )}{\mathbb{d}t}}}}}} & (2)\end{matrix}$

A typical cross correlation function is plotted in FIG. 52 (note thatthis cross correlation function depicts a system with two characteristictime delays, t1 and t2).

The most straightforward interpretations of cross correlation functionsare in the context of propagation problems. For non-dispersive signalpropagation of the type considered here, even in the presence ofadditive noise associated with the sensors, one can show that$\begin{matrix}{{{R_{12}(\tau)} = {R_{22}( {\tau - \frac{D}{V}} )}},} & (3)\end{matrix}$

where R22 is the autocorrelation of s2(t). A typical autocorrelationfunction is plotted in FIG. 53. Thus, the cross correlation of equation(2) will look like the autocorrelation of s2(t) shifted by the amountD/V along the correlation time axis. Using this fact, one can readilyinfer the delay time □ by searching for the peak magnitude of the crosscorrelation function (whose construction is described below), and thencomputing the velocity V using equation (1) since D is known. Thus, atwo-sensor system will permit the measurement of the speed V independentof the spatial spectral content of the snow surface.

Note that the separation D is shown with large separation for purposesof illustration; when in fact that distance will typically reflect asmall separation such as illustrated by the separation of the sensors1108 of FIG. 41.

There are a few practical considerations to be kept in mind whencomputing R12, and in interpreting its characteristics. First, unlikeautocorrelations, extraneous noise at the sensors 1604 a, 1604 b onlyreduces the relative contributions of individual correlation peaks andincreases the random error in the measurement; but it does not distortor bias the result, hence the time delay measured will be the true timedelay. Secondly, one should determine a priori if there are anysecondary propagation paths for the vibrational signal that first enterssensor 1604 a to reach sensor 1604 b before the ski slides over the snowthe distance D.

This may occur in skis or snowboards, as is shown in FIG. 54. Theboard/ski can support bending modes via flexing, which have acharacteristic (slowest) propagation speed “CB”. Also, the materialwithin the board can support the equivalent of acoustic (sound) waveswithin it, with characteristic propagation speed “CP”. This would leadto a cross con-elation having two correlation peaks, each of whichcorresponds to the delay time associated with transmitting thevibrational input at 1604 a to sensor 1604 b via bending andcompressional waves, respectively. If these wave speeds are comparablewith the skier's speed V, then one will not distinguish skiing speedfrom the natural vibrational response of the board/ski 1602.Fortunately, these vibrational wave speeds should be faster than theskier's speed, and thus appear at a much shorter delay time on thecorrelation plot: the characteristic wave speed in aluminum is 20,664feet/sec, in ice about 10,496 feet/sec, and in rubber about 7872feet/sec for compressional waves. The bending wave speed will typicallybe slower, but can only be computed for well known geometries andmaterial compositions, and is usually easier to measure in the labbeforehand. If there should ever be a problem in measuring the speed Vvia the cross correlation of equation (2), it will likely beattributable to this. Should that problem occur, one can readily getaround it by changing the sensor spacing D, which would thence change □.

The cross correlation is computed from digital samples via$\begin{matrix}{{{R_{12}( {r\quad\Delta\quad t} )} = {\frac{1}{N - r}{\sum\limits_{n = 1}^{N - r}{s_{2,n}s_{1,{n + r}}}}}},} & (4)\end{matrix}$

where r defines the sample lag number at which the cross correlation isbeing computed, N the number of sample points in the time records, andthe subscript n denotes the n-th element in the time record, and □t isthe sampling rate of the system. This function can be normalized to haveunit magnitude by dividing through by the square roots of the zero-delayauto correlations of the signals s1 and s2 (e.g., the variances of thesesignals): $\begin{matrix}{{{\rho( {r\quad\Delta\quad t} )} = \frac{R_{12}( {r\quad\Delta\quad t} )}{\sqrt{R_{1}(0)}\sqrt{R_{2}(0)}}}{for}} & (5) \\{{R_{1} = {\frac{1}{N}{\sum\limits_{n = 1}^{N}( s_{1,n} )^{2}}}};{R_{2} = {\frac{1}{N}{\sum\limits_{n = 1}^{N}{( s_{2,n} )^{2}.}}}}} & (6)\end{matrix}$

This simplifies the setting of thresholds for selecting the delay time □corresponding to the skier speed V. Also, one can restrict the set oflag numbers r if you already have some idea of the expected delays,given the speeds you expect to encounter skiing or boarding (or othersports, since these techniques apply to other sports and are discussedin the context of skiing for illustrative purposes only).

The means to test this measurement and processing methodology is tomount sensors on the board or ski, and first measure the correlationfunction of equation (4) for all r. Then, compute the speed V perequation (1), and compare it to that measured with a truth sensor, suchas a police radar gun, or a simple wind anemometer. Also, compute thestandard cross spectra function as found on most any spectrum analyzerto see if the phase of the cross spectra denotes a pure lag (aprogressive phase shift when unwrapped) over a range of frequencies (aswould be expected here). This method though requires that you computetwo FFTs, do a complex multiplication, and then compute the phase via anarctangent, all in real-time. If you see several delay times in thecross correlation, as might be found for a particularly floppy set ofskis with a very, very slow bending wave speed, move the sensors and seeif these peaks shift so as to separate out the propagation delay due toskiing. The only limitation here is the spatial coherence length of thesnow/board interface, which needs to be observed experimentally.

Regarding expected delays, consider the Table 2 of delay times (in msec)for two separations: D=1.5 ft (as might be found in a foot-to-footspacing on a board), and D=4 ft. The delay T1 corresponds to D=1.5 ft,and T2 corresponds to D=4 ft. TABLE 2 Delay processing times speed T1(msec) T2 (msec) 5 204.5 545 10 102.2 272.7 15 68.2 181.8 20 51.2 136.525 41 109.3 30 34.1 90.7 35 29.2 77.9

Table 2 shows that to resolve the speed to within 5 mph, whichrepresents one suitable quantizer for speed sensing for the invention,one needs to be able to resolve a time delay at the higher speeds ofabout 5 msec for the short baseline (D=1.5 ft) case. To resolve thiswith a finess of, e.g., one part in 10, you must sample at 0.5 msec,which implies a bandwidth of 2 kHz for the short baseline system. Thisis not an onerous sampling requirement, especially in view of modernprocessing capability. Nonetheless, this is a 2 kHz sample rate on twochannels (i.e., for the two sensors), sampled with simultaneity betterthan 0.5 msec as well (e.g., easily achievable inter-channel skew, evenfor a system without simultaneous sample and hold amplifiers).

Another implementation issue is the fact that the system will losetracking during airtime, or perhaps when carving an especiallyaggressive turn, especially in very soft snow. Thus, it is preferably toimplement a last estimate hold feature on the display of speedinformation: if the data is not good enough to update the speed (e.g.,if the signals drop below a certain level indicative of air, if an air“trigger signal” is used as a conditional trigger, or if the correlationthreshold level is not met), then continue to display the last valuemeasured.

Other speed measurement implementations are provided in FIGS. 55-57. InFIG. 55, the two sensors 1604′ are integrated beneath a snowboarder'sboots 1622, or even within the boots' soles. In FIG. 56, a multiplicityof sensors 1604″ is included with a ski 1620 (showing a binding 1622),and the cross correlation is computed across any pair so as to maximizethe signal to noise ratio, or even to adapt to differing snow conditionsor skier speeds. In FIG. 57, a two-dimensional array of sensors 1604′″is shown arranged around the boot mounts 1640 of a snowboard 1642, whereone may employ either “s1-s2” or “s3-s4” sensor pairs to measure Vdepending on which side of the board is dug in (so as to maximize thesensor signals). One may also employ either s1-s3 or s2-s4 to inferside-slip via correlation measurements as well.

An alternative speed measuring system 1650 is shown in FIGS. 58 and 59,incorporating a down-looking Doppler system: system 1650 utilizes“bistatic” sonar, while system 1650 a utilizes “monostatic”. All of thetransducers 1654 and their operating frequencies are chosen so that theresulting acoustic fields 1656 have wavelengths larger than thetransducer diameters, making the radiation and receive patterns broadand overlapping. The transmitter (the “pinger”) 1654 a transmit a pulse,a CW signal, or a band-limited FM signal, and the receiver 1654 b sensesthis signal and infers speed from the associated Doppler shift.

The system in FIG. 59 is of particular interest, as it combines transmitand receive functions in a single element, reducing cost. Further, ifone uses a pulsed signal in this configuration, then one could use itnot only to sense Doppler, but distance and height too (by applying atime gate to the return). A near gate would be set to preclude measuringrandom hops and skips, but will instead see true “air” when theski/board is sufficiently high above the snow. One rangefinding systemmanufactured by Polariod can function as such a system, with electronicsfor under $10.

Other Techniques for Power Estimation

Power can be used to quantitatively establish “bragging rights” amongusers, allowing them to compare level of effort expended during a run,over the course of a day, etc.

Power is defined conventionally as the rate of energy transfer into orout of a system. As such, power is an instantaneous quantity, ratherthan an integrative measure. Consequently, power can be determined asthat energy expended over a run, providing a suitable metric to measureand report.

There are three chief components leading to energy expenditure in sportssuch as skiing and snowboarding:

1. Frictional resistance as the vehicle moves across its supportingsurface, impeding the motion of the vehicle;

2. Air drag (both form drag and frictional resistance), impeding themotion of the vehicle/operator system;

3. Supporting the operator upright in the presence of external forces,such as those encountered when skiing over moguls, riding a mountainbike over rough terrain, or when countering the pull of a tow rope whenwater skiing.

Frictional drag can be modeled in a variety of ways. Nominally, if theresistance is viscous in nature, then the retarding force is linearlyproportional to the vehicles speed V:F _(d) =c·V,  (1)

where “c” is the viscous drag coefficient, which should be determinedempirically. Note that the frictional force is linearly proportional tothe velocity V; while in practice the proportionality is nonlinear, theapproximation will suffice for present purposes. The linear coefficientcan also be estimated, measured or ignored (since power units can beunitless and preferably correspond to suitable numbers to comparemultitudes of users in an easy manner). From conservation of energy,$\begin{matrix}{{{\frac{1}{2}m\quad V^{2}\sin^{2}\theta} = {{{mg}\quad\Delta\quad h} - {\int_{0}^{t_{f}}{{{cV}^{2}(t)}\sin^{2}\theta{\mathbb{d}t}}}}},} & (2)\end{matrix}$

where □ is the angle of the slope, “m” is the mass of the user (e.g.,skier+skis), and □h is the vertical drop between gates. Since thevelocity profile is linear over time, $\begin{matrix}{{{\int_{0}^{t_{f}}{{{cV}^{2}(t)}\sin^{2}\theta{\mathbb{d}t}}} = {\frac{1}{3}{cV}^{2}\sin^{2}\theta\quad t_{f}}},{{and}\quad{thence}}} & (3) \\{c = {{3\lbrack \frac{{{mg}\quad\Delta\quad h} - ( \frac{{mV}^{2}\sin^{2}\theta}{2} )}{V^{2}\sin^{2}\theta\quad t_{f}} \rbrack}.}} & (4)\end{matrix}$

With respect to the impact on energy expenditure during the activity,the instantaneous power loss is given by $\begin{matrix}{{P_{d}(t)} = \{ {\begin{matrix}{{{{F_{d}(t)} \cdot {V(t)}} = {{cV}^{2}(t)}};} & {{vehicle}\quad{in}\quad{contact}} \\{0;} & {{vehicle}\quad{not}\quad{in}\quad{contact}}\end{matrix}.} } & (5)\end{matrix}$

Assuming that the frictional coefficient is constant over the run, thenif one measures V(t), as discussed above or by some other estimation,then the total energy expenditure due to friction over a run is given by$\begin{matrix}{{E_{d} = {\int_{0}^{t_{end}}{{P_{d}(t)}{\mathbb{d}t}}}},} & (6)\end{matrix}$where tend is the finishing time.

The resistive force due to air frictional drag is in generalproportional to the square of the velocity, hence the energy loss over arun will be proportional to the time integral of this resistive forcetimes the velocity. The proportionality constant will in general bedifficult to estimate, or even measure. However, roughly it isproportional to a constant times the cross sectional (frontal) area ofthe user. One can get a first cut at this area by assuming that thewidth of a skier is a fixed proportion of their height, then from ameasurement of weight (measured, for example, using the FSR meanspreviously described) and a standard actuarial table for weight/heightcorrelation. Thus, $\begin{matrix}{{E_{a} = {{\int_{0}^{t_{end}}{{am}\quad{V^{3}(t)}{\mathbb{d}t}}} \cong {\sum\limits_{t = 1}^{(\frac{t_{end}}{\Delta\quad t})}{{{amV}^{3}( t_{i} )}\Delta\quad t}}}},} & (7)\end{matrix}$where “m” is the mass of the skier. The proportionality constant “a” isset heuristically.

Finally, the contribution to energy expenditure from supporting theoperator upright in the presence of external forces can be estimatedusing a system 1666 of FIG. 60, where the user 1670 wears anaccelerometer 1671 around her waist, capable of measuring the verticalcomponent of acceleration Δy(t). Further, the ski/board/boot sole 1672has a force measuring means 1674 (as discussed herein) to measure theforce component “F”. The operator 1670 will be dissipating energy bybending their knees, decelerating the mass of their upper body. Sincethe legs can be though of as rigid links with rotary springs at the kneeand hip joints, the force due to this deceleration will be transmittedto the force sensing means (springs transmit forces). This, theinstantaneous power dissipated in maintaining a tuck is given by$\begin{matrix}{P_{b} = {{{F(t)} \cdot \frac{\mathbb{d}{y(t)}}{\mathbb{d}t}} = {{F(t)} \cdot {\int^{t}{{y^{\prime\prime}(t)}{\mathbb{d}t}}}}}} & (8)\end{matrix}$

Note that this equation is not conditional with respect to vehiclecontact as per equation (5) of this section, as the reaction force Fgoes to zero when the vehicle leaves the surface. The energy expendedover a run due to this effort is then given by $\begin{matrix}{E_{b} = {\int_{0}^{t_{end}}{{F \cdot \lbrack {\int^{t}{{y^{\prime\prime}(t)}{\mathbb{d}t}}} \rbrack}{{\mathbb{d}t}.}}}} & (9)\end{matrix}$

In total, the energy expended over a run is given as the sum of thethree energy components:E _(total) =E _(d) +E _(a) +E _(b).  (10)

Alternate systems to measure the skier's hip position y(t) (shown inFIG. 60) is provided in FIGS. 61 and 62. In FIG. 61, a flexible element1680 is sewn into the skier's pants 1682, covering the leg 1684. A PVDFor NiTiNOL SMA strip 1686 is bonded to the element 1680, and will act asa large-area strain gage. When the skier bends his knees the gage 1686will stretch, and to first order this strain will be proportional to thechange in the leg's bend angle at the knee. By differentiating thissignal one can obtain a signal proportional to the velocity y(t)depicted above, but without using an accelerometer. Since one need notintegrate this signal to compute velocity or displacement, the energyexpenditure is computed simply as a multiplication.

Still another system for power measurement is shown in FIG. 62 In FIG.62, a force gage or compressive strain element 1700 is inserted into theinside of a tongue 1702 of a ski boot 1704. When the skier leansforward, the force on the tongue 1702 increases to first order inproportion to the angle of the lower leg with respect to the ski/board.Thus, one can measure a signal indicative of the quantity y(t) bymeasuring the force on the boot's tongue. Once again, since one need notintegrate this signal to compute velocity or displacement, the energyexpenditure is computed as a multiplication.

Other Techniques for Drop Distance

In one aspect, instantaneous height above the surface (a relative ratherthan an absolute measurement) is provided by the system of FIG. 59. Byusing a simple pulse output sound waveform, and applying a time gate tothe acoustic return, the system can sense the distance of askier/boarder above the ground from the round-trip time it takes thesignal to return to the sensor. This provides a measure of the skier'sinstantaneous height.

Other Techniques for Airtime

Several alternative airtime sensors are next shown, including one newsignal processor to detect transients to provide a “trigger” or “gate”for estimating airtime.

With a FSR (Force Sensing Resistor) one can detect the presence of askier in the vehicle (for instance, in the bindings if positionedbeneath the boot and above the binding), the skier's weight, and whetherthe skier is being supported by a surface or is “airborne”. A typicalFSR 1800 is sketched in FIG. 63. FSRs can be purchased from IEEInterlink for $2-$4 each in small quantities depending on the aperturesize. These pads consist of interdigitated electrodes 1802 over asemi-conductive polymer ink 1804. The resistance between the electrodes1802 decreases nonlinearly as a function of applied compressive load,and they exhibit high sensitivity. A PSA layer is generally applied toone side; a further encapsulant (say of polyurethane) is desirable for aharsh/wet environments. A typical FSR signal conditioning circuit isshown in FIG. 64 that provides a voltage indicative of the FSR'schanging resistance. Unlike accelerometers or induced-strain sensors(such as the AMP PVDF sensors), FSRs sense static loads.

Consider FIGS. 65 and 66. An FSR described above is placed in the loadpath of the skier, either beneath the boot 1808, within the boot's heel1809, within the ski/board, or beneath the ski/board 1810. Consequently,when the skier 1812 stands on the ski/board 1810, and when the ski/board1810 is on the ground, there is a reaction force FR pushing up againstthe skier 1812. This will be sensed by the FSR, as shown in FIG. 67,region “A”. When the skier 1812 is pushed by bumps and moguls this forcewill change, as shown in region “B”, FIG. 67, owing to Newton's secondlaw. When the skier/boarder 1812 leaves the ground, as shown in FIG. 66,then region “C” is realized and reaction force diminishes to zero as aneasily-sensed transient. This too will be sensed by the FSR, assuggested in FIG. 67, region D of Trace I. Trace II of FIG. 67 is closerto zero force (if not actually equal zero) and corresponds to the casewhereupon there is no residual compression of the FSR due to theclamping load of the binding, if the sensor is in the binding or bootheel (or due to residual mechanical stresses induced during manufactureif the sensor is embedded within the ski/board). Trace II, which shows ahigher “residual” load, reflects when these residual stresses arepresent, and needs to be quantified if the transient amplitude change inregion “C” is to be use as a trigger or gate to the airtime estimation.The skier/boarder 1812 becomes reacquainted with the supporting surfacein region “E”, as the reaction force may now actually peak owing to thecompressional transient; this too is measured by the FSR in the loadpath. The skier/boarder 1812 returns to “normal” travel again in region“F”.

The output of the FSR can in all likelihood be low-pass filtered ataround 20 Hz, since the latency in estimating liftoff can be about 500msec (i.e., a reasonable minimum airtime lower limit). Triggergeneration is effected using only a comparator or similar analogthresholding electronics based upon signal amplitude, and perhaps slewrate or hysteresis (probably not necessary); and there is no need tomeasure spectral changes. Unfortunately, FSRs do not have significantbandwidth and thus can limit the measurable vehicle speed.

In the user of PVDFs (i.e., the piezo foils discussed above), certaincare should be taken. First, they are only capable of measuring dynamicsignals: they will not measure a static load, or a static displacement.For static measurements (such as inferring weight as described above) orvery low frequency measurements (typically below 5 to 10 Hz), othersensors should be employed such as FSRs.

A second performance limitation of the PVDF is that these sensors arefar more sensitive to induced in-plane strains than to compressionalstrains. These strain axes 1-3 are defined in FIG. 68, showing one piezofoil 1900. The in-plane strains are in the “1” and “2” directions, withthe “1” direction being the “pull” direction for the PVDF (almost alwaysthe long axis for the AMP sensing strips) associated with the material'sprocessing. The compressional strain is in the “3” direction. Note thatthe electro-mechanical constitutive constants relating an input strainto an output voltage measured across the thickness of the sensor (wherethe electrodes are always placed) are approximately an order ofmagnitude larger in the “1” direction than in the “3” direction; whilethe values in the “2” and “3” directions are approximately equal. Thisis an artifact of the fabrication methodology for so-called “uniaxial”PVDF. Consequently, this makes the AMP PVDF strips excellent dynamicstrain gages.

This enhanced strain performance is not a problem if the sensor strip isattached to a rigid, non-bending surface, as suggested above (e.g., thehousing 32, FIG. 1A). In this configuration the piezo is rigidly gluedto an inflexible surface 1910, FIG. 69, and a rigid mass M is attachedto the top of the piezo 1912. Consequently, when the lower surface isvibrated, the mass M causes the piezo 1912 to compress owing to theinertial forces, leading to a voltage output □V across the sensor'sthickness proportional to the vibration, which is essentially how anaccelerometer works.

Consider a piezo strip 1920 attached to a flexible surface 1922, assuggested in FIG. 70. When the surface bends in response to an inputvibration, this induces an output in the sensor □V proportional to thebending strain. The vibration need not accelerate the mass M in thevertical direction to induce this output; so, if the surface is a ski,and the ski flexes irrespective of whether or not the ski is acceleratedvertically, you will measure an output that will typically swamp anysignal due to vertical acceleration or vibration. In this situation, youare measuring the flexural response of the ski, and not the verticalvibration induced by the ski's passage over a rough surface. In order tomeasure this vertical vibration, one needs to deconvolve the ski'sflexural dynamics, a significant challenge. Note also that the skiitself is acting as a filter, since it has natural modes of responsemuch like a guitar string or drum head, and very much wants to respondat those frequencies. This will skew and perhaps dominate anymeasurement of the vibrational spectra.

These problems are addressed in FIGS. 71 and 72. Consider a ski orsnowboard having two PVDF sensors deposited on it, one atop the ski andone below (or any symmetric arrangement about the midline of theski/board), registered spatially one above the other. These are laid upwith their polarization axes aligned, as suggested by the arrows inFIGS. 71, 72. In FIG. 71, the ski bends, and the top sensor sees acompressive strain, while the lower sees an extensive strain. Thus,charge will migrate to the outer surfaces of both piezos. If onemeasures the voltage potential across these two sensors the result willbe (ideally) zero; the same is true for bending in the oppositedirection, for higher-order modes, etc. In practice, the bending strainresponse is significantly diminished, with residual response due tomismatched sensors and positioning errors. One can think of thisarrangement as providing “common mode rejection” for bending strains. InFIG. 72, if a compressive stress is applied as from a verticalacceleration of the ski owing to its passage over an irregular surfacethen a potential difference is induced over the outer layers of thesensor composite, and a voltage V is measured.

An alternate means of achieving an analogous result on one side of thevehicle is to build a sandwich of two PVDF layers, as shown in FIG. 73.Here, the polarization axes are aligned in opposition. Unlike theprevious embodiment, this arrangement's voltage output is measured viathe connections shown at the left side 1980 of the sensor 1982, whichtap both the inner and outer electrodes of the piezo composite. Thisarrangement has proven to yield a superior acoustic receiver, andprovides common mode rejection to electrical interference such as fromradio transmitters.

For both embodiments of FIGS. 71/72 and 73, one can employ avoltage-follower circuit to drive long leads, if required.

FIG. 74 illustrates a gaming system 2200 which connects severalmountains 2202 a-2202 c via a WAN or the Internet 2208. A pluralityskier or snowboarder 2204 are on the mountains 2202; and each has a datatransmitting device 2206 (the device is illustrated in FIG. 75); andeach device 2206 includes functionality such as described herein toprovide performance data. In particular, each device 2206 includes amicroprocessor 2208 (or microcontroller or other intelligence sufficientto assist in acquiring data from connected transducers) and can includeone or more of the following: airtime sensor 2210 a, speed sensor 2210b, power sensor 2210 c and drop distance sensor 2210 d. If required, abattery drives the device 2206. The microprocessor 2208 collects datafrom one or more sensors 2210 (note that sensors 2210 can be simpletransducers connected through conditioning electronics 2212), processesthe data, and transmits the data to a data driver 2214, such as datasection 22, FIG. 1A. The data driver 2214 communicates with receivers(e.g., the receiver 72, FIG. 1B) at each respective lodge 2220 a-1220 cso that the data is available on the Internet 2208. In this manner, datafrom any mountain is collected for comparison to other players on othermountains. A main database 2222 keeps and stores all data for accessthrough the Internet 2208. For example, the database 2222 can include aWWW interface which all can access (if desired, or only if give accessauthority) to acquire and compare scores across the nation (or world).

Note that the game played by the system 2200 can be for airtime, speed,power, or drop distance, or a combination of one or more. Further, itshould be understood that the medium of skiing is shown illustratively,and that other sports are easily accomplished in a similar system. Byway of example, each person 2204 could be a mountain biker instead. Or,each mountain could be replaced by a lake or ocean and each person 2204can be a windsurfer.

Certain devices of the invention can also be incorporated into a bootbinding, such as shown in FIGS. 76 and 77. In FIG. 76, a ski binding2300 is shown; while in FIG. 77, a snowboarder binding 2302 is shown. Ineach case, a sensing unit 2304 such as described above is incorporatedinto the binding. The device 2304 can include, for example, an airtimedevice and/or a power sensor and/or a pitch-based speed sensor and/or analtimeter. A data transfer unit 2306 (e.g., a radio, inductive loop, IRtransmitter) connects to the unit 2304 so that data (e.g., airtime,power, speed and drop distance) can be relayed to the user (or to a dataunit or to the base station). For example, the user carries a sisterdata receive unit (not shown) that provides the user with the desireddata. Note that data transfer unit can be an IR transmitting section andthe receive data unit can be a datawatch, such as described above. Thedevice 2304 includes power and other circuitry so as to operate andacquire the appropriate data, as described above.

The advantage of the design of FIG. 76 is that a sensing unit accordingto the invention is not mounted directly on the ski (or snowboard) andis further protected from the environment. Also, it is more practical tomounting to a board or ski. Without such packaging advantage, it isdifficult, though not impossible, to package a sensing unit (such as anair meter or speed meter, described herein) onto a board withsufficiently small size and weight. Preferably, a device such as thedevice 1102 of FIG. 41 has only a depth of 0.300″ or less, and anoverall weight of less than ⅛ to ¼ pound. Such a size is preferred inorder to fit the device into a recessed area on the board withoutexcessive overhang or add-on weight. However, as in FIG. 77, this goalis relaxed somewhat.

Power can also be determined by other methods, in accord with theinvention. For example, with an accelerometer pointed up, relative tothe ski and perpendicular to the ground, when the user hits bumpyterrain, the accelerometer will have “peaks” and valleys. One techniquefor determining power is thus to count peaks past some predeterminedthreshold, such as shown in FIG. 78, which illustrates “5” peak signalswhich pass the threshold “k”. The value “5” does not have to correspondto a real unit, such as g's. The value of k can be set experimentallysuch as through the data unit described above. k should be above 1 G,for example, which is a constant force. That is, when the accelerometeris not pointed along the gravity vector, it might read “0” and will read“1”—and neither event should effect the power calculation.Alternatively, an exact determination of g's can be made and provided bythe sensor, and thus given to the user. However, this requires extensiveprocessing and is not overly practical. The goal here is to displayunits that are common to all. For example, power units could extend from0-10 (or 0-100) wherein, for example, a user with a 9 shows greatexertion as compared to a user with a “1” reading (or alternatively, a70 as compared to a 10 reading). It is thus important to make the powerdetermination at appropriate intervals, or at a set integration time.

FIG. 79 shows a sensor 2499 such as described herein including a dopplermodule 2500. The beam 2502 from the module 2500 extends backwards, orforwards, on the ski (or snowboard) 2506 and about 45 degrees to theside. In this manner, the beam 2502 need not extend through the board,such as described above; but can instead broadly illuminate a region2504 away from the ski 2506. Since the module 2500 is slightly above theboard, it can illuminate the region 2504 without going through the board2506. This greatly assists taking such measurements, for example, in theultrasound region since ultrasound does not transmit through boardswell. Similarly, for microwave, metal in the board can completely wipeout a signal return, effectively eliminating the speed measurement.

It should be noted that a power sensing unit can be made generically andsimply on a wrist watch, as discussed above. Such a unit is useful forvarious sports, such as basketball, to monitor a user's aggressivenessin play. As shown in FIG. 80, such a unit in the form of a watch 2600can provide data to a computer 2602 at the gaming site (FIG. 80 showsone user on a basketball court, for example; though the scene is equallyapplicable to other sports, e.g., soccer, football and hockey). Thecomputer 2602 and watch 2600 have data transfer capability such asthrough RF signals, known to those in the art. During play, the user2604 is effectively “monitored” so that the coach or owner caneffectively gauge performance and aggressiveness. The device within thewatch 2600 can include sensors such as described herein. The watch 2600further includes batteries and required circuitry.

The unit 2600′ could also be placed and/or sewn into a user's shorts, asshown in FIG. 81.

Certain sensing units of the invention require power. Often it isdesirable to turn the power off when the unit is not in use, such aswhen the user is in a bar. In accord with the invention, a FET switchcan be used for this purpose, such as known in the art. This savesbattery life.

Power and/or speed can also be measured and assessed by measuring signalPSD.

Barometers and altimeters, in accord with the invention, preferably“logic” out data at the base and peak of a mountain, so that data is notstored and recorded in these regions. This is similar to logic outregions such as airtime above 30 seconds, which likely does not occur,or for less than 1 second (or 2 second) which resembles walking andwhich should be ignored.

Note, if there is no airtime, often, the circuitry of the inventionshould operate to logic out drop distance too, such as shown in FIG. 82.

FIG. 83 illustrates one other embodiment wherein data from a sensor 2699such as described herein (e.g., a sensor such as an airtime sensor)transmits data to a user 2700 at the user's helmet 2702. A heads-updisplay 2704 and/or a microphone 2706 can be used to relay performancedata to the user 2700, for example by informing the user of “airtime”.If the user is a speed skier, the data is useful to modify form sincethey do not wish airtime. A base station computer can also monitor theairtime data which can then be evaluated later. A buzz sent to the mic2706 can similarly inform the user 1700. The heads-up display 2704 cantake the form of sunglasses; and the helmet 2702 is not required.

Sensing units of the invention can be integrated within many sportsimplements, such as shown in FIG. 84. Each implement of FIG. 84 includesa sensing unit 3000, described herein. The implements include, at least,ice skates, water skis 3004 (or wakeboards 3004), ski poles 3006,windsurfer 3008, surfboard 3010, tennis racquet 3012, skateboard 3014,roller blade 3016, and volleyball 3018. Other implements are within thescope of the invention.

Those skilled in the art should appreciate that changes can be madewithin the description above without departing from the scope of theinvention.

The invention thus attains the objects set forth above, among thoseapparent from preceding description. Since certain changes may be madein the above apparatus and methods without departing from the scope ofthe invention, it is intended that all matter contained in the abovedescription or shown in the accompanying drawing be interpreted asillustrative and not in a limiting sense.

It is also to be understood that the following claims are to cover allgeneric and specific features of the invention described herein, and allstatements of the scope of the invention which, as a matter of language,might be said to fall there between.

1. A method for determining airtime of a moving sportsman, comprising:processing data from one or more accelerometers attached to thesportsman, to determine when the sportsman is in free-fall; anddetermining a time period corresponding to the free-fall.
 2. The methodof claim 1, further comprising reporting the time period to the user asairtime.
 3. The method of claim 2, wherein reporting comprises utilizinga watch.
 4. The method of claim 2, wherein processing, determining andreporting comprises utilizing a single unit comprising a housing,microprocessor and display.
 5. The method of claim 1, wherein processingdata comprises processing data from tri-axial accelerometers, furthercomprising summing acceleration signals from the tri-axialaccelerometers, wherein the acceleration signals sum to zero when thesportsman is in free-fall.
 6. The method of claim 1, further comprisingdetermining a low frequency acceleration floor, wherein processing datacomprises determining acceleration signals below the floor, theacceleration signals below the floor indicating that the sportsman is infree-fall.
 7. The method of claim 6, determining a time periodcorresponding to the free-fall comprising timing a duration of theacceleration signals below the floor, wherein acceleration signals abovethe floor indicate an end to the free-fall.
 8. The method of claim 1,further comprising determining a reduction in a high frequency componentof at least one acceleration signal from the one or more accelerometers,the reduction in the high frequency component indicating that thesportsman is in free-fall.
 9. A system for determining airtime of amoving sportsman, comprising: at least one accelerometer for detectingacceleration of the sportsman; and a processor in communication with theat least one accelerometer, for processing signals from theaccelerometer to determine free-fall.
 10. The system of claim 9, thesignals comprising high-frequency acceleration signals indicative ofvibration as the sportsman contacts the ground, the processor comprisinga timer for timing a period of absence of the high frequency signalscorresponding to the free-fall.
 11. The system of claim 9, furthercomprising an altimeter for determining altitude; the processorprocessing the altitude to determine a drop in altitude during thefree-fall.
 12. The system of claim 9, further comprising a display fordisplaying the fi-ee-fall as airtime of the sportsman; the display, theaccelerometer and the processor configured with a common housing. 13.The system of claim 12, further comprising a wireless transmitterconfigured with the housing for reporting the free-fall to a remotelocation as airtime.
 14. A system for determining airtime of a movingsportsman, comprising: at least one accelerometer for generating signalsindicative of vibration; a pressure sensor for determining change inaltitude; and a processor for processing the signals from theaccelerometer and pressure sensor to determine airtime and drop distanceduring free-fall.
 15. The system of claim 14, further comprising a timerfor timing the free-fall.
 16. The system of claim 15, further comprisinga wireless transmitter for transmitting one or both of (a) the timedfree-fall to a remote location, as airtime and (b) the altitude.
 17. Thesystem of claim 15, further comprising a display for displaying thefree-fall as airtime.
 18. The system of claim 17, the accelerometer,altimeter, processor and display configured with a common housingattachable to the sportsman or a vehicle ridden by the sportsman.
 19. Anairtime measurement system, comprising: linear accelerometers formeasuring acceleration in three translational directions; a processorfor receiving and summing signals indicative of acceleration from thelinear accelerometers, the processor timing a period in which thesignals from the accelerometers sum to zero; wherein the processoridentifies the period in which the signals sum to zero as a period offree-fall.
 20. The system of claim 19, the processor configured todetermine the minimum distance traveled during the period of free-fallalong an axis of gravity according to the formula:d=vot+½gt2, when an initial downward velocity is known, and according tothe formula d=½gt2, when the initial downward velocity is unknown;wherein d is a distance traveled downward, g is acceleration due togravity, vo is the initial velocity downward, and t is the period offree-fall, in seconds.
 21. An accelerometer suite for determiningairtime of a vehicle ridden by a sportsman, comprising: three linearaccelerometers for outputting signals indicative of vibrational noise inthe vehicle; conditioning electronics for strengthening and filteringthe signals and outputting conditioned signals; interface electronics incommunication with the conditioning electronics, for converting theconditioned signals from analog to digital; and a processor forreceiving and processing the conditioned signals to determine airtime;wherein the processor identifies a period of absence in vibrationalnoise as a period of free-fall.
 22. The system of claim 21, furthercomprising a wireless transmitter for transmitting the free-fall to aremote location as airtime.
 23. The system of claim 21, furthercomprising a display for displaying the airtime; the accelerometers, theconditioning electronics, the processor and the interface electronicsconfigured with a common housing.
 24. The system of claim 21, furthercomprising: an altimeter for determining altitude or a GPS receiver fordetermining three-dimensional location; wherein the processor processesthe altitude or location to determine drop distance during free-fall.